14-Bit, 3 GSPS, JESD204B,
Dual Analog-to-Digital Converter
Data Sheet AD9208
Rev. 0 Document Feedback
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FEATURES
JESD204B (Subclass 1) coded serial digital outputs
Support for lane rates up to 16 Gbps per lane
1.65 W total power per channel at 3 GSPS (default settings)
Performance at −2 dBFS amplitude, 2.6 GHz input
SFDR = 70 dBFS
SNR = 57.2 dBFS
Performance at −9 dBFS amplitude, 2.6 GHz input
SFDR = 78 dBFS
SNR = 59.5 dBFS
Integrated input buffer
Noise density = −152 dBFS/Hz
0.975 V, 1.9 V, and 2.5 V dc supply operation
9 GHz analog input full power bandwidth (−3 dB)
Amplitude detect bits for efficient AGC implementation
2 integrated, wideband digital processors per channel
48-bit NCO
4 cascaded half-band filters
Phase coherent NCO switching
Up to 4 channels available
Serial port control
Integer clock with divide by 2 and divide by 4 options
Flexible JESD204B lane configurations
On-chip dither
APPLICATIONS
Diversity multiband and multimode digital receivers
3G/4G, TD-SCDMA, W-CDMA, and GSM, LTE, LTE-A
Electronic test and measurement systems
Phased array radar and electronic warfare
DOCSIS 3.0 CMTS upstream receive paths
HFC digital reverse path receivers
FUNCTIONAL BLOCK DIAGRAM
ADC
CORE
FAST
DETECT
SIGNAL
MONITOR
DIGITAL DOWN-
CONVERTER
CROSSBAR MUX
CROSSBAR MUX
PROGRAMMABLE
FIR FILTER
DIGITAL DOWN-
CONVERTER
14
14
BUFFER
VIN+A
VIN–A
VIN+B
CLK+
CLK–
VREF
PDWN/STBY
SYSREF±
AGND DRGND DGND
AVDD1
(0.975V)
DVDD
(0.975V)
DRVDD1
(0.975V)
DRVDD2
(1.9V)
SPIVDD
(1.9V)
AVDD2
(1.9V)
AVDD3
(2.5V)
A
VDD1_S
R
(0.975V)
SPI AND
CONTROL
REGISTERS
SDIO SCLK CSB
VIN–B
BUFFER
ADC
CORE
÷2
÷4
AD9208
SERDOUT0±
SERDOUT1±
SERDOUT2±
SERDOUT3±
SERDOUT4±
SERDOUT5±
SERDOUT6±
SERDOUT7±
JESD204B
LINK
AND
Tx
OUTPUTS
8
JESD204B
SUBCLASS 1
CONTROL
CLOCK
DISTRIBUTION
SYNCINB±
GPIO_A1
FD_A/GPIO_A0
FD_B/GPIO_B0
GPIO_B1
GPIO MUX
15547-001
Figure 1.
AD9208 Data Sheet
Rev. 0 | Page 2 of 136
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 3
General Description ......................................................................... 4
Specifications ..................................................................................... 5
DC Specifications ......................................................................... 5
AC Specifications .......................................................................... 6
Digital Specifications ................................................................... 7
Switching Specifications .............................................................. 9
Timing Specifications ................................................................ 10
Absolute Maximum Ratings .......................................................... 12
Thermal Resistance .................................................................... 12
ESD Caution ................................................................................ 12
Pin Configuration and Function Descriptions ........................... 13
Typical Performance Characteristics ........................................... 16
Equivalent Circuits ......................................................................... 22
Theory of Operation ...................................................................... 24
ADC Architecture ...................................................................... 24
Analog Input Considerations .................................................... 24
Voltage Reference ....................................................................... 28
DC Offset Calibration ................................................................ 29
Clock Input Considerations ...................................................... 29
Power-Down/Standby Mode..................................................... 31
Temperature Diode .................................................................... 31
ADC Overrange and Fast Detect .................................................. 33
ADC Overrange .......................................................................... 33
Fast Threshold Detection (FD_A and FD_B) ........................ 33
ADC Application Modes and JESD204B Tx Converter Mapping
........................................................................................................... 34
Programmable FIR filters .............................................................. 36
Supported Modes........................................................................ 36
Programming Instructions ........................................................ 38
Digital Downconverter (DDC) ..................................................... 40
DDC I/Q Input Selection .......................................................... 40
DDC I/Q Output Selection ....................................................... 40
DDC General Description ........................................................ 40
DDC Frequency Translation ..................................................... 43
DDC Decimation Filters ............................................................ 51
DDC Gain Stage ......................................................................... 57
DDC Complex to Real Conversion ......................................... 57
DDC Mixed Decimation Settings ............................................ 58
DDC Example Configurations ................................................. 59
DDC Power Consumption ........................................................ 63
Signal Monitor ................................................................................ 64
SPORT over JESD204B .............................................................. 65
Digital Outputs ............................................................................... 67
Introduction to the JESD204B Interface ................................. 67
JESD204B Overview .................................................................. 67
Functional Overview ................................................................. 68
JESD204B Link Establishment ................................................. 68
Physical Layer (Driver) Outputs .............................................. 70
fS × 4 Mode .................................................................................. 71
Setting Up the AD9208 digital interface .................................. 72
Deterministic Latency .................................................................... 78
Subclass 0 Operation .................................................................. 78
Subclass 1 Operation .................................................................. 78
Multichip Synchronization ............................................................ 80
Normal Mode .............................................................................. 80
Timestamp Mode ....................................................................... 80
SYSREF Input .............................................................................. 82
SYSREF± Setup/Hold Window Monitor ................................. 84
Latency ............................................................................................. 86
End to End Total Latency .......................................................... 86
Example Latency Calculations.................................................. 86
LMFC Referenced Latency ........................................................ 86
Test Modes ....................................................................................... 88
ADC Test Modes ........................................................................ 88
JESD204B Block Test Modes .................................................... 89
Serial Port Interface ........................................................................ 91
Configuration Using the SPI ..................................................... 91
Hardware Interface ..................................................................... 91
SPI Accessible Features .............................................................. 91
Memory Map .................................................................................. 92
Reading the Memory Map Register Table ............................... 92
Memory Map Register Details .................................................. 93
Applications Information ............................................................ 134
Power Supply Recommendations ........................................... 134
Layout Guidelines..................................................................... 135
AVDD1_SR (Pin E7) and AGND (Pin E6 and Pin E8) ........... 135
AD9208 Data Sheet
Rev. 0 | Page 4 of 136
GENERAL DESCRIPTION
The AD9208 is a dual, 14-bit, 3 GSPS analog-to-digital converter
(ADC). The device has an on-chip buffer and a sample-and-
hold circuit designed for low power, small size, and ease of use.
This product is designed to support communications applications
capable of direct sampling wide bandwidth analog signals of up
to 5 GHz. The −3 dB bandwidth of the ADC input is 9 GHz.
The AD9208 is optimized for wide input bandwidth, high sampling
rate, excellent linearity, and low power in a small package.
The dual ADC cores feature a multistage, differential pipelined
architecture with integrated output error correction logic. Each
ADC features wide bandwidth inputs supporting a variety of
user-selectable input ranges. An integrated voltage reference
eases design considerations. The analog input and clock signals
are differential inputs. The ADC data outputs are internally
connected to four digital downconverters (DDCs) through a
crossbar mux. Each DDC consists of up to five cascaded signal
processing stages: a 48-bit frequency translator (numerically
controlled oscillator (NCO)), and up to four half-band decimation
filters. The NCO has the option to select preset bands over the
general-purpose input/output (GPIO) pins, which enables the
selection of up to three bands. Operation of the AD9208 between
the DDC modes is selectable via SPI-programmable profiles.
In addition to the DDC blocks, the AD9208 has several functions
that simplify the automatic gain control (AGC) function in a
communications receiver. The programmable threshold detector
allows monitoring of the incoming signal power using the fast
detect control bits in Register 0x0245 of the ADC. If the input
signal level exceeds the programmable threshold, the fast detect
indicator goes high. Because this threshold indicator has low
latency, the user can quickly turn down the system gain to avoid
an overrange condition at the ADC input. In addition to the fast
detect outputs, the AD9208 also offers signal monitoring
capability. The signal monitoring block provides additional
information about the signal being digitized by the ADC.
The user can configure the Subclasss 1 JESD204B-based high
speed serialized output in a variety of one-lane, two-lane, four-
lane, and eight-lane configurations, depending on the DDC
configuration and the acceptable lane rate of the receiving logic
device. Multidevice synchronization is supported through the
SYSREF± and SYNCINB± input pins.
The AD9208 has flexible power-down options that allow
significant power savings when desired. All of these features can
be programmed using a 3-wire serial port interface (SPI).
The AD9208 is available in a Pb-free, 196-ball BGA, specified
over the −40°C to +85°C ambient temperature range. This
product is protected by a U.S. patent.
Note that throughout this data sheet, multifunction pins, such
as FD_A/GPIO_A0, are referred to either by the entire pin
name or by a single function of the pin, for example, FD_A,
when only that function is relevant.
PRODUCT HIGHLIGHTS
1. Wide, input −3 dB bandwidth of 9 GHz supports direct radio
frequency (RF) sampling of signals up to about 5 GHz.
2. Four integrated, wideband decimation filter and NCO
blocks supporting multiband receivers.
3. Fast NCO switching enabled through the GPIO pins.
4. A SPI controls various product features and functions to
meet specific system requirements.
5. Programmable fast overrange detection and signal
monitoring.
6. On-chip temperature diode for system thermal management.
7. 12 mm × 12 mm, 196-ball BGA.
Data Sheet AD9208
Rev. 0 | Page 5 of 136
SPECIFICATIONS
DC SPECIFICATIONS
AVDD1 = 0.975 V, AVDD1_SR = 0.975 V, AVDD2 = 1.9 V, AVDD3 = 2.5 V, DVDD = 0.975 V, DRVDD1 = 0.975 V, DRVDD2 = 1.9 V,
SPIVDD = 1.9 V, specified maximum sampling rate, 1.7 V p-p full-scale differential input, input amplitude (AIN) = −2.0 dBFS, L = 8, M = 2,
F = 1, −10°C ≤ TJ ≤ +120°C,1 unless otherwise noted. Typical specifications represent performance at TJ = 70°C (TA = 25°C).
Table 1.
Parameter Min Typ Max Unit
RESOLUTION 14 Bits
ACCURACY
No Missing Codes Guaranteed
Offset Error 0 %FSR
Offset Matching 0 %FSR
Gain Error −5.89 ±1 +5.89 %FSR
Gain Matching −2.9 ±0.2 +2.9 %FSR
Differential Nonlinearity (DNL) −0.63 ±0.4 +0.74 LSB
Integral Nonlinearity (INL) −26 ±6 +21 LSB
TEMPERATURE DRIFT
Offset Error ±15 ppm/°C
Gain Error 440 ppm/°C
INTERNAL VOLTAGE REFERENCE 0.5 V
INPUT-REFERRED NOISE 5.6 LSB rms
ANALOG INPUTS
Differential Input Voltage Range 1.7 V p-p
Common-Mode Voltage(VCM) 1.32 1.35 1.52 V
Differential Input Resistance 200 Ω
Differential Input Capacitance 0.25 pF
Differential Input Return Loss at 2.1 GHz2 −7 dB
−3 dB Bandwidth 9 GHz
POWER SUPPLY
AVDD1 0.95 0.975 1.0 V
AVDD2 1.85 1.9 1.95 V
AVDD3 2.44 2.5 2.56 V
AVDD1_SR 0.95 0.975 1.0 V
DVDD 0.95 0.975 1.0 V
DRVDD1 0.95 0.975 1.0 V
DRVDD2 1.85 1.9 1.95 V
SPIVDD 1.85 1.9 1.95 V
IAVDD1 640 765 mA
IAVDD2 790 885 mA
IAVDD3 110 120 mA
IAVDD1_SR 24 50 mA
IDVDD 480 1020 mA
IDRVDD13 320 590 mA
IDRVDD2 30 35 mA
ISPIVDD 1 5 mA
POWER CONSUMPTION
Total Power Dissipation (Including Output Drivers)4 3.3 W
Power-Down Dissipation 300 mW
Standby5 1.65 mW
1 The junction temperature (TJ) range of −10°C to +120°C translates to an ambient temperature (TA) range of −40°C to +85°C.
2 For more information, see the Analog Input Considerations section.
3 All lanes running. Power dissipation on DRVDD1 changes with lane rate and number of lanes used.
4 Default mode. No DDCs used.
5 Can be controlled by the SPI.
AD9208 Data Sheet
Rev. 0 | Page 6 of 136
AC SPECIFICATIONS
AVDD1 = 0.975 V, AVDD1_SR = 0.975 V, AVDD2 = 1.9 V, AVDD3 = 2.5 V, DVDD = 0.975 V, DRVDD1 = 0.975 V, DRVDD2 = 1.9 V,
SPIVDD = 1.9 V, specified maximum sampling rate, 1.7 V p-p full-scale differential input, default SPI settings, −10°C ≤ TJ ≤ +120°C,1
unless otherwise noted. Typical specifications represent performance at TJ = 70°C (TA = 25°C).
Table 2.
AIN = −2 dBFS AIN = −9 dBFS
Parameter2 Min Typ Max Min Typ Max Unit
NOISE DENSITY3
1.7 V p-p Setting −152 −152 dBFS/Hz
2.04 V p-p Setting −154 −154 dBFS/Hz
NOISE FIGURE 24.5 24.5 dB
SIGNAL-TO-NOISE RATIO (SNR)
fIN = 255 MHz 60.2 60.2 dBFS
fIN = 255 MHz (2.04 V p-p Setting) 61.4 61.8 dBFS
fIN = 765 MHz 59.8 60.2 dBFS
fIN = 900 MHz 59.5 60.2 dBFS
fIN = 1800 MHz 58.7 60.0 dBFS
fIN = 2100 MHz 58.2 59.8 dBFS
fIN = 2600 MHz 52.1 57.2 59.5 dBFS
fIN = 3950 MHz 55.1 58.6 dBFS
SIGNAL-TO-NOISE-AND-DISTORTION RATIO (SINAD)
fIN = 255 MHz 59.7 60.0 dBFS
fIN = 255 MHz (2.04 V p-p Setting) 60.0 61.5 dBFS
fIN = 765 MHz 58.8 60.0 dBFS
fIN = 900 MHz 58.6 59.9 dBFS
fIN = 1800 MHz 57.4 59.7 dBFS
fIN = 2100 MHz 56.7 59.4 dBFS
fIN = 2600 MHz 46.6 56.1 59.2 dBFS
fIN = 3950 MHz 52.8 58.2 dBFS
EFFECTIVE NUMBER OF BITS (ENOB)
fIN = 255 MHz 9.6 9.7 Bits
fIN = 765 MHz 9.5 9.7 dBFS
fIN = 900 MHz 9.4 9.7 Bits
fIN = 1800 MHz 9.2 9.6 Bits
fIN = 2100 MHz 9.1 9.6 Bits
fIN = 2600 MHz 7.5 9.0 9.5 Bits
fIN = 3950 MHz 8.5 9.4 Bits
SPURIOUS-FREE DYNAMIC RANGE (SFDR), SECOND OR THIRD HARMONIC
fIN = 255 MHz 71 78 dBFS
fIN = 255 MHz (2.04 V p-p Setting) 65 83 dBFS
fIN = 765 MHz 71 79 dBFS
fIN = 900 MHz 71 78 dBFS
fIN = 1800 MHz 69 81 dBFS
fIN = 2100 MHz 67 73 dBFS
fIN = 2600 MHz 51 70 78 dBFS
fIN = 3950 MHz 58 73 dBFS
Data Sheet AD9208
Rev. 0 | Page 7 of 136
AIN = −2 dBFS AIN = −9 dBFS
Parameter2 Min Typ Max Min Typ Max Unit
WORST OTHER, EXCLUDING SECOND OR THIRD HARMONIC
fIN = 255 MHz −89 −90 dBFS
fIN = 255 MHz (2.04 V p-p Setting) −90 −90 dBFS
fIN = 765 MHz −90 −89 dBFS
fIN = 900 MHz −89 −90 dBFS
fIN = 1800 MHz −81 −94 dBFS
fIN = 2100 MHz −80 −98 dBFS
fIN = 2600 MHz −75 −84 −90 dBFS
fIN = 3950 MHz −80 −90 dBFS
TWO-TONE, THIRD-ORDER INTERMODULATION DISTORTION (IMD3)
fIN1 = 1.842 GHz, fIN2 = 1.847 GHz, AIN1 and AIN2 = −8.0 dBFS −73 dBFS
fIN1 = 1.842 GHz, fIN2 = 1.847 GHz, AIN1 and AIN2 = −15.0 dBFS −87 dBFS
fIN1 = 2.62 GHz, fIN2 = 2.69 GHz, AIN1 and AIN2 = −8.0 dBFS −69 dBFS
fIN1 = 2.62 GHz, fIN2 = 2.69 GHz, AIN1 and AIN2 = −15.0 dBFS −88 dBFS
fIN1 = 2.62 GHz, fIN2 = 2.69 GHz, AIN1 and AIN2 = −8.0 dBFS; Full-Scale Voltage
(VFS) = 1.13 V p-p
−75 dBFS
fIN1 = 2.62 GHz, fIN2 = 2.69 GHz, AIN1 and AIN2 = −15.0 dBFS; VFS = 1.13 V p-p −111 dBFS
CROSSTALK4 >90 >90 dB
Overrange Condition5 >90 >90 dB
ANALOG INPUT BANDWIDTH, FULL POWER6 5 5 GHz
1 The junction temperature (TJ) range of −10°C to +120°C translates to an ambient temperature (TA) range of −40°C to+ 85°C.
2 See the AN-835 Application Note, Understanding High Speed ADC Testing and Evaluation, for definitions and for details on how these tests were completed.
3 Noise density is measured at a low analog input frequency (30 MHz).
4 Crosstalk is measured at 950 MHz with a −1.0 dBFS analog input on one channel, and no input on the adjacent channel.
5 The overrange condition is specified with 3 dB of the full-scale input range.
6 Full power bandwidth is the bandwidth of operation in which proper ADC performance can be achieved.
DIGITAL SPECIFICATIONS
AVDD1 = 0.975 V, AVDD1_SR = 0.975 V, AVDD2 = 1.9 V, AVDD3 = 2.5 V, DVDD = 0.975 V, DRVDD1 = 0.975 V, DRVDD2 = 1.9 V,
SPIVDD = 1.9 V, specified maximum sampling rate, 1.7 V p-p full-scale differential input, AIN = −2.0 dBFS, L = 8, M = 2, F = 1, −10°C ≤
TJ ≤ +120°C,1 unless otherwise noted. Typical specifications represent performance at TJ = 70°C (TA = 25°C).
Table 3.
Parameter Min Typ Max Unit
CLOCK INPUTS (CLK+, CLK−)
Logic Compliance LVDS/LVPECL
Differential Input Voltage 300 800 1800 mV p-p
Input Common-Mode Voltage 0.675 V
Input Resistance (Differential) 106 Ω
Input Capacitance 0.9 pF
Differential Input Return Loss at 3 GHz2 −9.4 dB
SYSTEM REFERENCE (SYSREF) INPUTS (SYSREF+, SYSREF−)
Logic Compliance LVDS/LVPECL
Differential Input Voltage 400 800 1800 mV p-p
Input Common-Mode Voltage 0.675 2.0 V
Input Resistance (Differential) 18 kΩ
Input Capacitance (Differential) 1 pF
LOGIC INPUTS (SDIO, SCLK, CSB, PDWN/STBY, FD_A/GPIO_A0,
FD_B/GPIO_B0, GPIO_A1, GPIO_B1)
Logic Compliance CMOS
Logic 1 Voltage 0.65 × SPIVDD V
Logic 0 Voltage 0 0.35 × SPIVDD V
Input Resistance 30 kΩ
AD9208 Data Sheet
Rev. 0 | Page 8 of 136
Parameter Min Typ Max Unit
LOGIC OUTPUTS (SDIO, FD_A, FD_B)
Logic Compliance CMOS
Logic 1 Voltage (IOH = 4 mA) SPIVDD − 0.45V V
Logic 0 Voltage (IOL = 4 mA) 0 0.45 V
SYNCIN INPUT (SYNCINB+/SYNCINB−)
Logic Compliance LVDS/LVPECL
Differential Input Voltage 400 800 1800 mV p-p
Input Common-Mode Voltage 0.675 2.0 V
Input Resistance (Differential) 18 kΩ
Input Capacitance 1 pF
SYNCINB+ INPUT
Logic Compliance CMOS
Logic 1 Voltage 0.9 × DRVDD1 2 × DRVDD1 V
Logic 0 Voltage 0.1 × DRVDD1 V
Input Resistance 2.6 kΩ
DIGITAL OUTPUTS (SERDOUTx±, x = 0 TO 7)
Logic Compliance SST
Differential Output Voltage 360 560 770 mV p-p
Differential Termination Impedance 80 100 120 Ω
1 The junction temperature (TJ) range of −10°C to +120°C translates to an ambient temperature (TA) range of −40°C to+85°C.
2 Reference impedance = 100 Ω.
Data Sheet AD9208
Rev. 0 | Page 9 of 136
SWITCHING SPECIFICATIONS
AVDD1 = 0.975 V, AVDD1_SR = 0.975 V, AVDD2 = 1.9 V, AVDD3 = 2.5 V, DVDD = 0.975 V, DRVDD1 = 0.975 V, DRVDD2 = 1.9 V,
SPIVDD = 1.9 V, specified maximum sampling rate, 1.7 V p-p full-scale differential input, AIN = −2.0 dBFS, default SPI settings, −10°C ≤
TJ ≤ +120°C,1 unless otherwise noted. Typical specifications represent performance at TJ = 70°C (TA = 25°C).
Table 4.
Parameter Min Typ Max Unit
CLOCK
Clock Rate (at CLK+/CLK− Pins) 3 6 GHz
Sample Rate2 2500 3000 3100 MSPS
Clock Pulse Width High 161.29 166.67 192.31 ps
Clock Pulse Width Low 161.29 166.67 192.31 ps
OUTPUT PARAMETERS
Unit Interval (UI)3 62.5 66.67 592.6 ps
Rise Time (tR) (20% to 80% into 100 Ω Load) 26 ps
Fall Time (tF) (20% to 80% into 100 Ω Load) 26 ps
Phase-Locked Loop (PLL) Lock Time 5 ms
Data Rate per Channel (Nonreturn to Zero)4 1.6875 15 16 Gbps
LATENCY5
Pipeline Latency6 75 Clock cycles
Fast Detect Latency 26 Clock cycles
WAKE-UP TIME
Standby 400 µs
Power-Down 15 ms
NCO CHANNEL SELECTION TO OUTPUT 8 Clock cycles
APERTURE
Aperture Delay (tA) 250 ps
Aperture Uncertainty (Jitter, tJ) 55 fs rms
Out of Range Recovery Time 1 Clock cycles
1 The junction temperature (TJ) range of −10°C to +120°C translates to an ambient temperature (TA) range of −40°C to +85°C.
2 The maximum sample rate is the clock rate after the divider.
3 Baud rate = 1/UI. A subset of this range can be supported.
4 Default L = 8. This number can be changed based on the sample rate and decimation ratio.
5 No DDCs used. L = 8, M = 2, and F = 1.
6 Refer to the Latency section for more details.
AD9208 Data Sheet
Rev. 0 | Page 10 of 136
TIMING SPECIFICATIONS
Table 5.
Parameter Description Min Typ Max Unit
CLK+ to SYSREF+ TIMING REQUIREMENTS
tSU_SR Device clock to SYSREF+ setup time −65 ps
tH_SR Device clock to SYSREF+ hold time 95 ps
SPI TIMING REQUIREMENTS
tDS Setup time between the data and the rising edge of SCLK 2 ns
tDH Hold time between the data and the rising edge of SCLK 2 ns
tCLK Period of the SCLK 40 ns
tS Setup time between CSB and SCLK 2 ns
tH Hold time between CSB and SCLK 2 ns
tHIGH Minimum period that SCLK must be in a logic high state 10 ns
tLOW Minimum period that SCLK must be in a logic low state 10 ns
tACCESS Maximum time delay between the falling edge of SCLK and
output data valid for a read operation
6 10 ns
tDIS_SDIO Time required for the SDIO pin to switch from an output to an
input, relative to the SCLK rising edge (not shown in Figure 4)
10 ns
Timing Diagrams
ABCDE FGH I J CONVERTER0
SAMPLE N – 75 MSB
SERDOUT0–
SERDOUT0+
CLK–
CLK+
CLK–
CLK+
ABCDE FGH I J CONVERTER0
SAMPLE N – 75 LSB
SERDOUT1–
SERDOUT1+
ABCDE FGH I J CONVERTER0
SAMPLE N – 74 MSB
SERDOUT2–
SERDOUT2+
ABCDE FGH I J CONVERTER0
SAMPLE N – 74 LSB
SERDOUT3–
SERDOUT3+
ABCDE FGH I J CONVERTER1
SAMPLE N – 75 MSB
SERDOUT4–
SERDOUT4+
ABCDE FGH I J CONVERTER1
SAMPLE N – 75 LSB
SERDOUT5–
SERDOUT5+
ABCDE FGH I J CONVERTER1
SAMPLE N – 74 MSB
SERDOUT6–
SERDOUT6+
ABCDE FGH I J CONVERTER1
SAMPLE N – 74 LSB
SERDOUT7–
SERDOUT7+
APERTURE DELAY
N – 74
N – 73
N – 72
N – 1
N + 1
SAMPLE N
N – 75
ANALOG
INPUT
SIGNAL
SAMPLE N – 75 AND N – 74
ENCODED INTO ONE
8-BIT/10-BIT SYMBOL
15547-002
Figure 2. Data Output Timing Diagram
Data Sheet AD9208
Rev. 0 | Page 11 of 136
CLK–
CLK+
SYSREF–
SYSREF+
t
H_SR
t
SU_SR
15547-003
Figure 3. SYSREF± Setup and Hold Timing Diagram
S
CLK
SDIO
CSB
DON’T CARE DON’T CARE
t
S
t
DS
t
H
t
CLK
t
ACCESS
t
DH
t
LOW
t
HIGH
DON’T CARE R/W A14 A13 A12 A11 A10 A9 A8 A7 D5 D4 D3 D2 D0D1 DON’T CARE
15547-004
Figure 4. SPI Interface Timing Diagram
AD9208 Data Sheet
Rev. 0 | Page 12 of 136
ABSOLUTE MAXIMUM RATINGS
Table 6.
Parameter Rating
Electrical
AVDD1 to AGND 1.05 V
AVDD1_SR to AGND 1.05 V
AVDD2 to AGND 2.0 V
AVDD3 to AGND 2.70 V
DVDD to DGND 1.05 V
DRVDD1 to DRGND 1.05 V
DRVDD2 to DRGND 2.0 V
SPIVDD to DGND 2.0 V
AGND to DRGND −0.3 V to +0.3 V
AGND to DGND −0.3 V to +0.3 V
DGND to DRGND −0.3 V to +0.3 V
VIN±x to AGND AGND − 0.3 V to AVDD3 + 0.3 V
CLK± to AGND AGND − 0.3 V to AVDD1 + 0.3 V
SCLK, SDIO, CSB to DGND DGND − 0.3 V to SPIVDD + 0.3 V
PDWN/STBY to DGND DGND − 0.3 V to SPIVDD + 0.3 V
SYSREF± to AGND 2.5 V
SYNCINB± to DRGND 2.5 V
Junction Temperature Range (TJ) −40°C to +125°C
Storage Temperature Range,
Ambient (TA)
−65°C to +150°C
Stresses at or above those listed under Absolute Maximum
Ratings may cause permanent damage to the product. This is a
stress rating only; functional operation of the product at these
or any other conditions above those indicated in the operational
section of this specification is not implied. Operation beyond
the maximum operating conditions for extended periods may
affect product reliability.
THERMAL RESISTANCE
Thermal performance is directly linked to printed circuit board
(PCB) design and operating environment. Close attention to
PCB thermal design is required. θJA is the natural convection
junction-to-ambient thermal resistance measured in a one cubic
foot sealed enclosure. θJC is the junction to case thermal resistance.
Table 7. Thermal Resistance
Package Type θJA θ
JC_TOP Ψ
JB Ψ
JT Unit
BP-196-41 16.26 1.4 5.44 1.68 °C/W
1 Test Condition 1: Thermal impedance simulated values are based on JEDEC
2S2P thermal test board with 190 thermal vias. See JEDEC JESD51.
ESD CAUTION
Data Sheet AD9208
Rev. 0 | Page 13 of 136
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
1
DENOTES CLOCK DOMAIN.
2
DENOTES SYSREF± DOMAIN.
3
DENOTES ISOLATION DOMAIN.
1 2 3 4 5 6 7 8 9 1011121314
AAVDD2 AVDD2 AVDD1 AVDD1
1
AVDD1
1
AGND
1
CLK+ CLK– AGND
1
AVDD1
1
AVDD1
1
AVDD1 AVDD2 AVDD2
BAVDD2 AVDD2 AVDD1 AVDD1
1
AGND AGND
1
AGND
1
AGND
1
AGND
1
AGND AVDD1
1
AVDD1 AVDD2 AVDD2
CAVDD2 AVDD2 AVDD1 AGND AGND AGND
1
AGND
1
AGND
1
AGND
1
AGND AGND AVDD1 AVDD2 AVDD2
DAVDD3 AGND AGND AGND AGND AGND AGND
1
AGND
1
AGND AGND AGND AGND AGND AVDD3
EVIN–B AGND AGND AGND AGND AGND
2AVDD1_SR
AGND
2
AGND AGND AGND AGND AGND VIN–A
FVIN+B AGND AGND AGND AGND AGND SYSREF+ SYSREF– AGND AGND AGND AGND AGND VIN+A
GAVDD3 AGND AGND AGND AGND AGND AGND AGND AGND AGND AGND AGND AGND AVDD3
HAGND AGND AGND AGND AGND AGND AGND AGND AGND VREF AGND AGND AGND AGND
JAGND AGND AGND AGND AGND AGND AGND AGND AGND AGND AGND AGND AGND AGND
KAGND
3
AGND
3
AGND
3
AGND
3
AGND
3
AGND
3
AGND
3
AGND
3
AGND
3
AGND
3
AGND
3
AGND
3
AGND
3
AGND
3
LDGND GPIO_B1 SPIVDD FD_B/
GPIO_B0 CSB SCLK SDIO PDWN/
STBY
FD_A/
GPIO_A0 SPIVDD GPIO_A1 DGND DGND DGND
MDGND DGND DRGND DRGND DRVDD1 DRVDD1 DRVDD1 DRVDD1 DRGND DRGND DRVDD1 DRGND DRVDD2 DVDD
NDVDD DVDD DRGND
SERDOUT7+ SERDOUT6+ SERDOUT5+ SERDOUT4+ SERDOUT3+ SERDOUT2+ SERDOUT1+ SERDOUT0+
DRGND SYNCINB+ DVDD
PDVDD DVDD DRGND
SERDOUT7– SERDOUT6– SERDOUT5– SERDOUT4– SERDOUT3– SERDOUT2– SERDOUT1– SERDOUT0–
DRGND SYNCINB– DVDD
A
D9208
15547-005
Figure 5. Pin Configuration (Top View)
AD9208 Data Sheet
Rev. 0 | Page 14 of 136
Table 8. Pin Function Descriptions1
Pin No. Mnemonic Type Description
Power Supplies
A3, A12, B3, B12, C3, C12 AVDD1 Power Analog Power Supply (0.975 V Nominal).
A4, A5, A10, A11, B4, B11 AVDD12 Power
Analog Power Supply for the Clock Domain (0.975 V
Nominal).
A1, A2, A13, A14, B1, B2, B13, B14,
C1, C2, C13, C14
AVDD2 Power Analog Power Supply (1.9 V Nominal).
D1, D14, G1, G14 AVDD3 Power Analog Power Supply (2.5 V Nominal).
E7 AVDD1_SR Power Analog Power Supply for SYSREF± (0.975 V Nominal).
L3, L10 SPIVDD Power Digital Power Supply for SPI (1.9 V Nominal).
M14, N1, N2, N14, P1, P2, P14 DVDD Power Digital Power Supply (0.975 V Nominal).
M5 to M8, M11 DRVDD1 Power Digital Driver Power Supply (0.975 V Nominal).
M13 DRVDD2 Power Digital Driver Power Supply (1.9 V Nominal).
B5, B10, C4, C5, C10, C11, D2 to D6,
D9 to D13, E2 to E5, E9 to E13,
F2 to F6, F9 to F13, G2 to G13,
H1 to H9, H11 to H14, J1 to J14
AGND Ground
Analog Ground. These pins connect to the analog
ground plane.
A6, A9, B6 to B9, C6 to C9, D7, D8 AGND2 Ground Ground Reference for the Clock Domain.
E6, E8 AGND3 Ground Ground Reference for SYSREF±.
K1 to K14 AGND4 Ground Isolation Ground.
L1, L12 to L14, M1, M2 DGND Ground Digital Control Ground Supply. These pins connect to
the digital ground plane.
M3, M4, M9, M10, M12, N3, N12,
P3, P12
DRGND Ground
Digital Driver Ground Supply. These pins connect to
the digital driver ground plane.
Analog
E1, F1 VIN−B, VIN+B Input ADC B Analog Input Complement/True.
E14, F14 VIN−A, VIN+A Input ADC A Analog Input Complement/True.
A7, A8 CLK+, CLK− Input Clock Input True/Complement.
H10 VREF Input/DNC
0.50 V Reference Voltage Input/Do Not Connect. This
pin is configurable through the SPI as a no connect or
an input. Do not connect this pin if using the internal
reference. This pin requires a 0.50 V reference voltage
input if using an external voltage reference source.
CMOS Inputs/Outputs
L2 GPIO_B1 Input/output GPIO B1.
L4 FD_B/GPIO_B0 Input/output Fast Detect Outputs for Channel B/GPIO B0.
L9 FD_A/GPIO_A0 Input/output Fast Detect Outputs for Channel A/GPIO A0.
L11 GPIO_A1 Input/output GPIO A1.
Digital Inputs
F7, F8 SYSREF+, SYSREF− Input Active High JESD204B LVDS System Reference Input
True/Complement.
N13 SYNCINB+ Input Active Low JESD204B LVDS/CMOS Sync Input True.
P13 SYNCINB− Input Active Low JESD204B LVDS Sync Input Complement.
Data Outputs
N4, P4 SERDOUT7+, SERDOUT7− Output Lane 7 Output Data True/Complement.
N5, P5 SERDOUT6+, SERDOUT6− Output Lane 6 Output Data True/Complement.
N6, P6 SERDOUT5+, SERDOUT5− Output Lane 5 Output Data True/Complement.
N7, P7 SERDOUT4+, SERDOUT4− Output Lane 4 Output Data True/Complement.
N8, P8 SERDOUT3+, SERDOUT3− Output Lane 3 Output Data True/Complement.
N9, P9 SERDOUT2+, SERDOUT2− Output Lane 2 Output Data True/Complement.
N10, P10 SERDOUT1+, SERDOUT1− Output Lane 1 Output Data True/Complement.
N11, P11 SERDOUT0+, SERDOUT0− Output Lane 0 Output Data True/Complement.
Data Sheet AD9208
Rev. 0 | Page 15 of 136
Pin No. Mnemonic Type Description
Digital Controls
L8 PDWN/STBY Input
Power-Down Input (Active High). The operation of
this pin depends on the SPI mode and can be
configured as power-down or standby.
L5 CSB Input SPI Chip Select (Active Low).
L6 SCLK Input SPI Serial Clock.
L7 SDIO Input/output SPI Serial Data Input/Output.
1 See the Theory of Operation section and the Applications Information section for more information on isolating the planes for optimal performance.
2 Denotes clock domain.
3 Denotes SYSREF± domain.
4 Denotes isolation domain.
AD9208 Data Sheet
Rev. 0 | Page 16 of 136
TYPICAL PERFORMANCE CHARACTERISTICS
AVDD1 = 0.975 V, AVDD1_SR = 0.975 V, AVDD2 = 1.9 V, AVDD3 = 2.5 V, DVDD = 0.975 V, DRVDD1 = 0.975 V, DRVDD2 = 1.9 V,
SPIVDD = 1.9 V, sampling rate = 3000 MHz, 1.7 V p-p full-scale differential input, DDC decimation rate = 8, default buffer current settings,
TA = 25°C, 128,000 fast Fourier transform (FFT) sample, unless otherwise noted. See Table 10 for the recommended settings.
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN
= –2dBFS
SNR = 60.2dBFS
SFDR = 71dBFS
ENOB = 9.6BITS
NSD = –152.0dBFS/Hz
BUFFER CURRENT = 400µA
15547-006
Figure 6. Single-Tone FFT at fIN = 255 MHz
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN
= –2dBFS
SNR = 60dBFS
SFDR = 71dBFS
ENOB = 9.6BITS
NSD = –151.8dBFS/Hz
BUFFER CURRENT = 500µA
15547-007
Figure 7. Single-Tone FFT at fIN = 765 MHz
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN
= –2dBFS
SNR = 59.9dBFS
SFDR = 71dBFS
ENOB = 9.6BITS
NSD = –151.6dBFS/Hz
BUFFER CURRENT = 500µA
15547-008
Figure 8. Single-Tone FFT at fIN = 905 MHz
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN
= –2dBFS
SNR = 57.9dBFS
SFDR = 69dBFS
ENOB = 9.2BITS
NSD = –149.7dBFS/Hz
BUFFER CURRENT = 500µA
15547-009
Figure 9. Single-Tone FFT at fIN = 1807 MHz
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN
= –9dBFS
SNR = 60.4dBFS
SFDR = 81dBFS
ENOB = 9.7BITS
NSD = –152.1dBFS/Hz
BUFFER CURRENT = 500µA
15547-010
Figure 10. Single-Tone FFT at fIN = 1807 MHz, AIN = −9 dBFS
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN
= –2dBFS
SNR = 58.0dBFS
SFDR = 67dBFS
ENOB = 9.2BITS
NSD = –149.7dBFS/Hz
BUFFER CURRENT = 500µA
15547-011
Figure 11. Single-Tone FFT at fIN = 2100 MHz
Data Sheet AD9208
Rev. 0 | Page 17 of 136
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN
= –9dBFS
SNR = 50.2dBFS
SFDR = 75dBFS
ENOB = 9.7BITS
NSD = –152.0dBFS/Hz
BUFFER CURRENT = 500µA
15547-012
Figure 12. Single-Tone FFT at fIN = 2100 MHz, AIN = −9 dBFS
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN
= –2dBFS
SNR = 57.2dBFS
SFDR = 70dBFS
ENOB = 9.1BITS
NSD = –149.0dBFS/Hz
BUFFER CURRENT = 700µA
15547-013
Figure 13. Single-Tone FFT at fIN = 2600 MHz
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN
= –9dBFS
SNR = 59.9dBFS
SFDR = 78dBFS
ENOB = 9.7BITS
NSD = –151.7dBFS/Hz
BUFFER CURRENT = 500µA
15547-014
Figure 14. Single-Tone FFT at fIN = 2600 MHz, AIN = −9 dBFS
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN
= –2dBFS
SNR = 54.9dBFS
SFDR = 58dBFS
ENOB = 8.4BITS
NSD = –146.7dBFS/Hz
BUFFER CURRENT = 700µA
15547-015
Figure 15. Single-Tone FFT at fIN = 3957 MHz
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN
= –9dBFS
SNR = 58.2dBFS
SFDR = 73dBFS
ENOB = 9.34BITS
NSD = –150dBFS/Hz
BUFFER CURRENT = 700µA
15547-016
Figure 16. Single-Tone FFT at fIN = 3957 MHz, AIN = −9 dBFS
61
60
59
58
57
56
55
54
SNR (dBFS)
INPUT FREQUENCY (MHz)
155 455 755 1055 1355 1655 1955 2255 2555 2855 3155 3455 3755
–9dBFS
–2dBFS
15547-017
Figure 17. SNR vs. Input Frequency (fIN); AIN = −2 dBFS and −9 dBFS
AD9208 Data Sheet
Rev. 0 | Page 18 of 136
0
10
20
30
40
50
60
70
80
90
SFDR (dBFS)
INPUT FREQUENCY (MHz)
–9dBFS
–2dBFS
155 455 755 1055 1355 1655 1955 2255 2555 2855 3205 3505 3805
15547-018
Figure 18. SFDR vs. Input Frequency (fIN); AIN = −2 dBFS and −9 dBFS
155 455 755 1055 1355 1655 1955 2255 2555 2855 3205 3505 3805
–80
–70
–60
–50
–40
–30
–20
–10
0
HD2 (dBc)
INPUT FREQUENCY (MHz)
–9dBFS
–2dBFS
15547-019
Figure 19. HD2 vs. Input Frequency (fIN); AIN = −2 dBFS and −9 dBFS
–90
–80
–70
–60
–50
–40
–30
–20
–10
0
HD3 (dBc)
INPUT FREQUENCY (MHz)
–9dBFS
–2dBFS
155 455 755 1055 1355 1655 1955 2255 2555 2855 3205 3505 3805
15547-020
Figure 20. HD3 vs. Input Frequency (fIN); AIN = −2 dBFS and −9 dBFS
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN1
AND A
IN2
= –8dBFS
SFDR = 72dBFS
IMD2 = 72dBFS
IMD3 = 73dBFS
BUFFER CURRENT = 500µA
15547-021
Figure 21. Two-Tone FFT; fIN1 = 1821.5 MHz, fIN2 = 1831.5 MHz;
AIN1 and AIN2 = −8 dBFS
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN1
AND A
IN2
= –15dBFS
SFDR = 75dBFS
IMD2 = 75dBFS
IMD3 = 87dBFS
BUFFER CURRENT = 500µA
15547-022
Figure 22. Two-Tone FFT; fIN1 = 1821.5 MHz, fIN2 = 1831.5 MHz;
AIN1 and AIN2 = −15 dBFS
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN1
AND A
IN2
= –8dBFS
SFDR = 67dBFS
IMD2 = 67dBFS
IMD3 = 69dBFS
BUFFER CURRENT = 600µA
15547-023
Figure 23. Two-Tone FFT; fIN1 = 2621.5 MHz, fIN2 = 2631.5 MHz;
AIN1 and AIN2 = −8 dBFS
Data Sheet AD9208
Rev. 0 | Page 19 of 136
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN1
AND A
IN2
= –15dBFS
SFDR = 75dBFS
IMD2 = 75dBFS
IMD3 = 88dBFS
BUFFER CURRENT = 600µA
15547-024
Figure 24. Two-Tone FFT; fIN1 = 2621.5 MHz, fIN2 = 2631.5 MHz;
AIN1 and AIN2 = −15 dBFS
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN1
AND A
IN2
= –8dBFS
SFDR = 67dBFS
IMD2 = 67dBFS
IMD3 = 75dBFS
BUFFER CURRENT = 600µA
15547-025
Figure 25. Two-Tone FFT; fIN1 = 2621.5 MHz, fIN2 = 2631.5 MHz;
Full-Scale Voltage = 1.1 V p-p; AIN1 and AIN2 = −8 dBFS
0
–120
–100
–80
–60
–40
–20
0 150 300 450 600 750 900 1050 1200 1350 1500
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN1
AND A
IN2
= –15dBFS
SFDR = 86dBFS
IMD2 = 106dBFS
IMD3 = 111dBFS
BUFFER CURRENT = 800µA
15547-026
Figure 26. Two-Tone FFT; fIN1 = 2621.5 MHz, fIN2 = 2631.5 MHz;
Full-Scale Voltage = 1.1 V p-p; AIN1 and AIN2 = −15 dBFS
–130
–110
–90
–70
–50
–30
–10
–187.5 –150.0 –112.5 –75.0 –37.5 0 37.5 75.0 112.5 150.0 187.5
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN1
AND A
IN2
= –15dBFS
NCO FREQUENCY = 1842.5MHz
SFDR = 80dBFS
15547-227
Figure 27. Two-Tone FFT; fIN1 = 1800 MHz, fIN2 = 2100 MHz
fCLK = 2.94912 GHz; Decimation Ratio = 8, NCO Frequency = 1874.28 MHz
–130
–110
–90
–70
–50
–30
–10
–187.5 –150.0 –112.5 –75.0 –37.5 0 37.5 75.0 112.5 150.0 187.5
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN1
AND A
IN2
= –15dBFS
NCO FREQUENCY = 2176.9MHz
SFDR = 94dBFS
15547-228
Figure 28. Two-Tone FFT; fIN1 = 1800 MHz, fIN2 = 2100 MHz
fCLK = 2.94912 GHz; Decimation Ratio = 8, NCO Frequency = 2176.92 MHz
–120
–100
–80
–60
–40
–20
0
–95 –89 –83 –77 –71 –65 –59 –53 –47 –41 –35 –29 –23 –17 –11 –7
SFDR/IMD3 (dBc AND dBFS)
INPUT AMPLITUDE (dBFS)
IMD3 (dBFS)
IMD3 (dBc)
SFDR (dBFS)
SFDR (dBc)
15547-229
Figure 29. Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with
fIN1 = 1821.5 MHz, fIN2 = 1831.5 MHz
AD9208 Data Sheet
Rev. 0 | Page 20 of 136
–120
–100
–80
–60
–40
–20
0
–95 –89 –83 –77 –71 –65 –59 –53 –47 –41 –35 –29 –23 –17
SFDR/IMD3 (dBc AND dBFS)
INPUT AMPLITUDE (dBFS)
IMD3 (dBFS)
IMD3 (dBc)
SFDR (dBFS)
SFDR (dBc)
15547-230
–11 –7
Figure 30. Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with
fIN1 = 2621.5 MHz, fIN2 = 2631.5 MHz
–40
–30
–20
–10
0
10
20
30
40
50
60
70
80
90
100
110
–95 –89 –83 –77 –71 –65 –59 –53 –47 –41 –35 –29 –23 –17 –11 –5 –1
SNR/SFDR (dBc AND dBFS)
INPUT AMPLITUDE (dBFS)
SNR (dBc)
SNR (dBFS)
SFDR (dBc)
SFDR (dBFS)
15547-027
Figure 31. SNR/SFDR vs. Input Amplitude (AIN), fIN = 950 MHz
–40
–30
–20
–10
0
10
20
30
40
50
60
70
80
90
100
110
–95 –89 –83 –77 –71 –65 –59 –53 –47 –41 –35 –29 –23 –17 –11 –5 –1
SNR/SFDR (dBc AND dBFS)
INPUT AMPLITUDE (dBFS)
SNR (dBc)
SNR (dBFS)
SFDR (dBc)
SFDR (dBFS)
15547-028
Figure 32. SNR/SFDR vs. Input Amplitude (AIN), fIN = 1800 MHz
50
55
60
65
70
75
80
–100 102030405060708090100110120
SNR/SFDR (dBFS)
T
J
(°C)
SNR (dBFS)
SFDR (dBFS)
15547-030
Figure 33. SNR/SFDR vs. Junction Temperature (TJ), fIN = 950 MHz, AIN = −9 dBFS
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
–10 0 10 20 30 40 50 60 70 80 90 100 110 120
POWER (W)
T
J
(°C)
TOTAL POWER (W)
AVDD1 + AVDD2 + AVDD3 POWER (W)
DVDD + SPIVDD POWER (W)
DRVDD1 + DRVDD2 POWER (W)
15547-031
Figure 34. Power vs. Junction Temperature (TJ), fIN = 950 MHz
52
53
54
55
56
57
58
59
60
255 655 1055 1455 1855 2255 2655 3055 3455 3855
SNR (dBFS)
ANALOG INPUT FREQUENCY (MHz)
500mV p-p
1200mV p-p
1800mV p-p
200mV p-p
1000mV p-p
1500mV p-p
2000mV p-p
15547-032
Figure 35. SNR vs. Analog Input Frequency (fIN) vs. Various Clock Amplitude in
Differential Voltages, AIN = −2dBFS
Data Sheet AD9208
Rev. 0 | Page 21 of 136
55
56
57
58
59
60
61
2400 2500 2600 2700 2800 2900 3000 3100
SNR (dBFS)
SAMPLE FREQUENCY (MHz)
–2dBFS
–9dBFS
15547-033
Figure 36. SNR vs. Sample Frequency (fS), fIN = 1.8 GHz; AIN = −2 dBFS and −9 dBFS
0
10
20
30
40
50
60
70
80
90
2400 2500 2600 2700 2800 2900 3000 3100
SFDR (dBFS)
SAMPLE FREQUENCY (MHz)
–2dBFS
–9dBFS
15547-238
Figure 37. SFDR vs. Sample Frequency (fS), fIN = 1.8 GHz; AIN = −2 dBFS and
−9 dBFS
0
1.0
0.5
1.5
2.0
2.5
3.0
3.5
4.0
2400 2500 2600 2700 2800 2900 3000 3100
POWER DISSIPATION (W)
SAMPLE FREQUENCY (MHz)
ANALOG POWER
DIGITAL POWER
DRIVER POWER
TOTAL POWER
15547-034
Figure 38. Power Dissipation vs. Sample Frequency (fS), fIN = 1.8 GHz; AIN = −2 dBFS
–15
–14
–13
–12
–11
–10
–9
–8
–7
–6
–5
–4
–
3
100 2100 4100 6100 8100 10100 12100
AMPLITUDE (dB)
FREQUENCY (MHz)
15547-035
Figure 39. Input Bandwidth (See Figure 55 for the Input Configuration)
0
80000
70000
60000
50000
40000
30000
20000
10000
NUMBER OF HITS
OUTPUT CODE
5.6LSB rms
N – 25
N – 23
N – 21
N – 19
N – 17
N – 15
N – 13
N – 10
N – 8
N – 6
N – 4
N – 2
N
N + 2
N + 4
N + 6
N + 8
N + 10
N + 12
N + 14
N + 16
N + 18
N + 20
N + 22
N + 24
15547-036
Figure 40. Input Referred Noise Histogram
AD9208 Data Sheet
Rev. 0 | Page 22 of 136
EQUIVALENT CIRCUITS
0.3pF
AVDD3
VIN+x
AVDD3
100
100
AVDD3
AVDD3
VIN–x
0.3pF
AVDD3
AIN
CONTROL
(SPI)
V
CM
BUFFER
15547-037
Figure 41. Analog Inputs
106
16k
AVDD1
CLK+
CLK–
AVDD1
16k
V
CM
= 0.65V
15547-038
Figure 42. Clock Inputs
130k
10k100
10k100
1.9pF
130k
AVDD1_SR
SYSREF+
SYSREF–
LEVEL
TRANSLATOR V
CM
= 0.65V
AVDD1_SR
1.9pF
15547-039
Figure 43. SYSREF± Inputs
OUTPUT
DRIVER
EMPHASIS/SWING
CONTROL (SPI)
DRVDD
SERDOUTx+
x = 0, 1, 2, 3, 4, 5, 6, 7
SERDOUTx–
x = 0, 1, 2, 3, 4, 5, 6, 7
DATA+
DATA–
DRVDD
DRGND
DRGND
15547-040
Figure 44. Digital Outputs
130k
2.6k
10k100
10k100
1.9pF
130k
DRVDD1
DRVDD1
SYNCINB+
SYNCINB–
DRGND
DRGND
DRGND
DRGND
DRGND
LEVEL
TRANSLATOR V
CM
= 0.65V
SYNCINB PIN
CONTROL (SPI)
CMOS PATH
DRVDD1
1.9pF
15547-041
Figure 45. SYNCINB± Inputs
Data Sheet AD9208
Rev. 0 | Page 23 of 136
56k
SCLK
SPIVDD
SPIVDD
ESD
PROTECTED
ESD
PROTECTED
DGND
DGND
DGND
15547-042
Figure 46. SCLK Input
56k
CSB
SPIVDD
ESD
PROTECTED
ESD
PROTECTED
DGND
DGND
15547-043
Figure 47. CSB Input
56k
SDIO
SPIVDD
SPIVDD
ESD
PROTECTED
ESD
PROTECTED
DGND
SPIVDD
DGND
SDI
SDO
DGND
DGND
15547-044
Figure 48. SDIO Input
56k
PDWN/STBY
SPIVDD
ESD
PROTECTED
ESD
PROTECTED
DGND
DGND
DGND
PDWN
CONTROL (SPI)
15547-045
Figure 49. PDWN/STBY Input
VREF
AGND
AVDD2
VCM OUTPUT
TEMPERATURE DIODE
VOLTAGE OUTPUT
EXTERNAL REFERENCE
VOLTAGE INPUT
VREF PIN
CONTROL (SPI)
15547-046
Figure 50. VREF Input/Output
56k
FD_A/GPIO_A0,
FD_B/GPIO_B0
SPIVDD
SPIVDD
ESD
PROTECTED
ESD
PROTECTED
DGND
FD PIN CONTROL (SPI)
SPIVDD
DGND
NCO BAND SELECT
FD
JESD204B LMFC
JESD204B SYNC~
DGND
DGND
15547-047
Figure 51. FD_A/GPIO_A0, FD_B/GPIO_B0
SPIVDD
56k
SPIVDD
ESD
PROTECTED
ESD
PROTECTED
DGND DGND
DGND
SDI
G
PIO_A1/GPIO_B1
GPIO_A1/GPIO_B1
PIN CONTROL (SPI)
NCO BAND SELECT
CHIP TRANSFER
15547-048
Figure 52. GPIO_A1/GPIO_B1
AD9208 Data Sheet
Rev. 0 | Page 24 of 136
THEORY OF OPERATION
The AD9208 has two analog input channels and up to eight
JESD204B output lane pairs. The ADC samples wide bandwidth
analog signals of up to 5 GHz. The actual −3 dB roll-off of the
analog inputs is 9 GHz. The AD9208 is optimized for wide input
bandwidth, high sampling rate, excellent linearity, and low
power in a small package.
The dual ADC cores feature a multistage, differential pipelined
architecture with integrated output error correction logic. Each
ADC features wide bandwidth inputs supporting a variety of
user-selectable input ranges. An integrated voltage reference
eases design considerations.
The AD9208 has several functions that simplify the AGC
function in a communications receiver. The programmable
threshold detector allows monitoring of the incoming signal
power using the fast detect output bits of the ADC. If the input
signal level exceeds the programmable threshold, the fast detect
indicator goes high. Because this threshold indicator has low
latency, the user can quickly turn down the system gain to avoid
an overrange condition at the ADC input.
The Subclass 1 JESD204B-based high speed serialized output data
lanes can be configured in one-lane (L = 1), two-lane (L = 2),
four-lane (L = 4), and eight-lane (L = 8) configurations, depending
on the sample rate and the decimation ratio. Multiple device
synchronization is supported through the SYSREF± and
SYNCINB± input pins. The SYSREF± pin in the AD9208 can
also be used as a timestamp of data as it passes through the
ADC and out of the JESD204B interface.
ADC ARCHITECTURE
The architecture of the AD9208 consists of an input buffered
pipelined ADC. The input buffer provides a termination
impedance to the analog input signal. This termination
impedance is set to 200 . The equivalent circuit diagram of the
analog input termination is shown in Figure 29. The input
buffer is optimized for high linearity, low noise, and low power
across a wide bandwidth.
The input buffer provides a linear high input impedance (for
ease of drive) and reduces kickback from the ADC. The
quantized outputs from each stage are combined into a final
14-bit result in the digital correction logic. The pipelined
architecture permits the first stage to operate with a new input
sample; at the same time, the remaining stages operate with the
preceding samples. Sampling occurs on the rising edge of the clock.
ANALOG INPUT CONSIDERATIONS
The analog input to the AD9208 is a differential buffer. The
internal common-mode voltage of the buffer is 1.35 V. The
clock signal alternately switches the input circuit between
sample mode and hold mode.
Either a differential capacitor or two single-ended capacitors (or
a combination of both) can be placed on the inputs to provide a
matching passive network. These capacitors ultimately create a
low-pass filter that limits unwanted broadband noise. For more
information, refer to the Analog Dialogue article “Transformer-
Coupled Front-End for Wideband A/D Converters”
(Volume 39, April 2005). In general, the precise front-end
network component values depend on the application.
Figure 53 shows the differential input return loss curve for the
analog inputs across a frequency range of 100 MHz to 10 GHz.
The reference impedance is 100 .
00
SDD11
5.0
–5.0
2.0
1.0
–1.0
FREQUENCY (100MHz TO 10GHz)
–2.0
0.5
–0.5
0.2
–0.2
m5
m4
m3
m2
m1
m1
FREQUENCY = 100MHz
SDD11 = 0.301/–8.069
IMPEDANCE= Z0 × (1.838 – j0.171)
m2
FREQUENCY = 1GHz
SDD11 = 0.352/–73.534
IMPEDANCE= Z0 × (0.947 – j0.731)
m3
FREQUENCY = 3GHz
SDD11 = 0.496/175.045
IMPEDANCE= Z0 × (0.337 – j0.038)
m4
FREQUENCY = 4GHz
SDD11 = 0.500/136.667
IMPEDANCE = Z0 × (0.379 – j0.347)
m5
FREQUENCY = 5GHz
SDD11 = 0.475/79.360
IMPEDANCE= Z0 × (0.737 – j0.889)
15547-254
Figure 53. Differential Input Return Loss
For best dynamic performance, the source impedances driving
VIN+x and VIN−x must be matched such that common-mode
settling errors are symmetrical. These errors are reduced by the
common-mode rejection of the ADC. An internal reference
buffer creates a differential reference that defines the span of the
ADC core.
Maximum SNR performance is achieved by setting the ADC to
the largest span in a differential configuration. For the AD9208,
the available span is programmable through the SPI port from
1.13 V p-p to 2.04 V p-p differential, with 1.7 V p-p differential
being the default.
Data Sheet AD9208
Rev. 0 | Page 25 of 136
Differential Input Configurations
There are several ways to drive the AD9208, either actively or
passively. Optimum performance is achieved by driving the
analog input differentially.
For applications where SNR and SFDR are key parameters,
differential transformer coupling is the recommended input
configuration (see Figure 54 and Table 9) because the noise
performance of most amplifiers is not adequate to achieve the
true performance of the AD9208.
For low to midrange frequencies, a double balun or double
transformer network (see Figure 54 and Table 9) is recommended
for optimum performance of the AD9208. For higher frequencies
in the second or third Nyquist zones, it is recommended to
remove some of the front-end passive components to ensure
wideband operation (see Figure 55 and Table 9).
ADC
200
C3
C2
C1
C4
R1
NOTES:
1. SEE TABLE 9 FOR COMPONENT VALUES
R2
R2
R3
C3
C2
R1 R3
MARKI
BAL-0006
15547-050
Figure 54. Differential Transformer Coupled Configuration for the AD9208
15547-331
ADC
MARKI
BAL-0009
25
25
25
0.1µ
F
0.1µF
0.1µF 200
10
2510
Figure 55. Input Network Configuration for Frequencies > 5 GHz
Table 9. Differential Transformer-Coupled Input Configuration Component Values
Frequency Range Transformer R1 R2 R3 C1 C2 C3 C4
<5000 MHz BAL-0006 25 Ω 25 Ω 10 Ω 0.1 F 0.1 F 0.4 pF 0.4 pF
AD9208 Data Sheet
Rev. 0 | Page 26 of 136
Input Common Mode
The analog inputs of the AD9208 are internally biased to the
common-mode voltage, as shown in Figure 57. The common-
mode buffer has a limited range in that the performance suffers
greatly if the common-mode voltage drops by more than 50 mV on
either side of the nominal value.
For dc-coupled applications, the recommended operation procedure
is to export the common-mode voltage to the VREF pin using
the SPI writes listed in this section. The common-mode voltage
must be set by the exported value to ensure proper ADC
operation. Disconnect the internal common-mode buffer from
the analog input using Register 0x1908.
When performing SPI writes for dc coupling operation, use the
following register settings in order:
8. Set Register 0x1908, Bit 2 to disconnect the internal
common-mode buffer from the analog input. Note that
this is a local register.
9. Set Register 0x18A6 to 0x00 to turn off the voltage
reference.
10. Set Register 0x18E6 to 0x00 to turn off the temperature
diode export.
11. Set Register 0x18E3, Bit 6 to 1 to turn on the VCM export.
12. Set Register 0x18E3, Bits[5:0] to the buffer current setting
(Register 0x1A4C and Register 0x1A4D) to improve the
accuracy of the common-mode export.
Figure 56 shows the block diagram representation of a
dc-coupled application.
ADC
ADC
AMP A
V
OCM
V
OCM
VREF
V
CM
EXPORT SELECT
SPI REGISTERS 0x1908,
0x18A6, 0x18E3, 0x18E6)
ADC
AMP B
15547-051
Figure 56. DC-Coupled Application Using the AD9208
Data Sheet AD9208
Rev. 0 | Page 27 of 136
Analog Input Buffer Controls and SFDR Optimization
V
IN+x
100
100
AVDD3
A
VDD3
0.3pF
AVDD3
V
IN–x
AVDD3
REG
(0x0008,
0x1908)
REG (0x0008, 0x1A4C,
0x1A4D, 0x1910)
AVDD3
0.3pF
15547-052
Figure 57. Analog Input Controls
The AD9208 input buffer offers flexible controls for the analog
inputs, such as buffer current, dc coupling, and input full-scale
adjustment. All the available controls are shown in Figure 57.
Using Register 0x1A4C and Register 0x1A4D, the buffer behavior
on each channel can be adjusted to optimize the SFDR over various
input frequencies and bandwidths of interest. Use Register 0x1910
to change the internal reference voltage. Changing the internal
reference voltage results in a change in the input full-scale voltage.
When the input buffer current in Register 0x1A4C and
Register 0x1A4D is set, the amount of current required by the
AVDD3 supply changes. This relationship is shown in Figure 58.
For a complete list of buffer current settings, see Table 46.
0.17
0.18
0.19
0.2
0.21
0.22
0.23
0.24
0.25
0.26
400 500 600 700
AVDD3 CURRENT (A)
BUFFER CURRENT SETTING (µA)
15547-053
Figure 58. AVDD3 Current (IAVDD3) vs. Buffer Current Setting (Buffer Control 1
Setting in Register 0x1A4C and Buffer Control 2 Setting in Register 0x1A4D)
Table 10 shows the recommended values for the buffer current
for various Nyquist zones.
Table 10. SFDR Optimization for Input Frequencies
Frequency Register 0x1A4C and Register 0x1A4D
DC to 1500 MHz 400 µA/500 µA
1500 MHz to 3000 MHz 500 µA
>3000 MHz 500 µA/700 µA
Dither
The AD9208 has internal on-chip dither circuitry that improves
the ADC linearity and SFDR, particularly at smaller signal
levels. A known but random amount of white noise is injected
into the input of the AD9208. This dither improves the small
signal linearity within the ADC transfer function and is
precisely subtracted out digitally. The dither is turned on by
default and does not reduce the ADC input dynamic range. The
data sheet specifications and limits are obtained with the dither
turned on.
The dither is on by default. It is not recommended to turn it off.
Absolute Maximum Input Swing
The absolute maximum input swing allowed at the inputs of the
AD9208 is 5.8 V p-p differential. Signals operating near or at
this level can cause permanent damage to the ADC. See Table 6
for more information.
AD9208 Data Sheet
Rev. 0 | Page 28 of 136
ADC
CORE
INPUT FULL SCALE
RANGE ADJUST
SPI REGISTER
(0x1910)
VREF PIN
CONTROL SPI
REGISTER
(0x18A6)
VFS
ADJUST
VIN+A/VIN+B
VIN–A/VIN–B
VREF
INTERNAL
0.5V
REFERENCE
GENERATOR
15547-054
Figure 59. Internal Reference Configuration and Controls
VREF PIN
AND VFS
CONTROL
VFS
ADJUST
VREFINPU
T
0.1µF 0.1µF
V
OUT
V
IN
ADC
INTERNAL
0.5V
REFERENCE
GENERATOR
SETGND
NCNC
ADR130
15547-056
Figure 60. External Reference Using the ADR130
VOLTAGE REFERENCE
A stable and accurate 0.5 V voltage reference is built into the
AD9208. This internal 0.5 V reference sets the full-scale input
range of the ADC. The full-scale input range can be adjusted via
the ADC input full-scale control register (Register 0x1910). For
more information on adjusting the input swing, see Table 46.
Figure 59 shows the block diagram of the internal 0.5 V reference
controls.
The SPI Register 0x18A6 enables the user to either use this
internal 0.5 V reference, or to provide an external 0.5 V
reference. When using an external voltage reference, provide a
0.5 V reference. The full-scale adjustment is made using the SPI,
irrespective of the reference voltage. For more information on
adjusting the full-scale level of the AD9208, refer to the Memory
Map section.
The SPI writes required to use the external voltage reference, in
order, are as follows:
1. Set Register 0x18E3 to 0x00 to turn off the VCM export.
2. Set Register 0x18E6 to 0x00 to turn off the temperature
diode export.
3. Set Register 0x18A6 to 0x01 to turn on the external voltage
reference.
The use of an external reference may be necessary, in some
applications, to enhance the gain accuracy of the ADC or to
improve thermal drift characteristics. Figure 61 shows the
typical drift characteristics of the internal 0.5 V reference.
0.5060
0.5055
0.5050
0.5045
0.5040
0.5035
0.5030
–10 10 30 50 70 90 110 130
BAND GAP VOLTAGE (V)
JUNCTION TEMPERATURE (°C)
15547-055
Figure 61. Typical VREF Drift
The external reference must be a stable 0.5 V reference. The
ADR130 is a sufficient option for providing the 0.5 V reference.
Figure 60 shows how the ADR130 can be used to provide the
external 0.5 V reference to the AD9208. The dashed lines show
unused blocks within the AD9208 while using the ADR130 to
provide the external reference.
Data Sheet AD9208
Rev. 0 | Page 29 of 136
DC OFFSET CALIBRATION
The AD9208 contains a digital filter to remove the dc offset
from the output of the ADC. For ac-coupled applications, this
filter can be enabled by writing 0x86 to Register 0x0701. The
filter computes the average dc signal and it is digitally subtracted
from the ADC output. As a result, the dc offset is improved to
better than 70 dBFS at the output. Because the filter does not
distinguish between the source of dc signals, this feature can be
used when the signal content at dc is not of interest. The filter
corrects dc up to ±512 codes and saturates beyond that.
CLOCK INPUT CONSIDERATIONS
For optimum performance, drive the AD9208 sample clock
inputs (CLK+ and CLK−) with a dierential signal. is signal is
ac-coupled to the CLK+ and CLK− pins via a transformer or clock
drivers. These pins are biased internally and require no
additional biasing.
Figure 62 shows the differential input return loss curve for the
clock inputs across a frequency range of 100 MHz to 6 GHz.
The reference impedance is 100 .
00
SDD11
5.0
–5.0
2.0
1.0
–1.0
FREQUENCY (100MHz TO 6GHz)
–2.0
0.5
–0.5
0.2
–0.2
m1
FREQUENCY = 2.503GHz
SDD11 = 0.313/–173.307
IMPEDANCE = Z0 × (0.524 – j0.042)
m2
FREQUENCY = 2.996GHz
SDD11 = 0.337/169.383
IMPEDANCE = Z0 × (0.499 – j0.070)
m3
FREQUENCY = 3.104GHz
SDD11 = 0.332/165.502
IMPEDANCE = Z0 × (0.508 – j0.095)
m4
FREQUENCY = 6GHz
SDD11 = 0.271/54.790
IMPEDANCE = Z0 × (1.218 – j0.581)
m1
m2
m4
15547-057
Figure 62. Differential Input Return Loss for the CLK± Inputs
Figure 63 shows a preferred method for clocking the AD9208.
The low jitter clock source is converted from a single-ended
signal to a differential signal using an RF transformer.
1:2Z
CLOCK INPUT
ADC
CLK+
CLK–
15547-058
Figure 63. Transformer-Coupled Differential Clock
Another option is to ac couple a differential CML or LVPECL
signal to the sample clock input pins, as shown in Figure 64 and
Figure 65.
ADC
CLOCK
INPUT
CLK+
CLK–
150150
LVDS
DRIVER
100
DIFFERENTIAL
TRACE
15547-059
Figure 64. Differential LVPECL Sample Clock
ADC
CLOCK
INPUT
CLK+
CLK–
CML
DRIVER
DIFFERENTIAL
TRACE
15547-060
Figure 65. Differential CML Sample Clock
ADC
ADC
CLOCK
INPUT
CLK+
CLK–
DAC
CLOCK
INPUT
CLKOUT+
CLKOUT–
15547-061
Figure 66. Clock Output Clocking the AD9208
AD9208 Data Sheet
Rev. 0 | Page 30 of 136
Clock Duty Cycle Considerations
Typical high speed ADCs use both clock edges to generate a
variety of internal timing signals. The AD9208 contains an
internal clock divider and a duty cycle stabilizer comprised of
DCS1 and DCS2, which is enabled by default. In applications
where the clock duty cycle cannot be guaranteed to be 50%, a
higher multiple frequency clock along with the usage of the
clock divider is recommended.
When it is not possible to provide a higher frequency clock, it is
recommended to turn on the DCS using Register 0x011C and
Register 0x011E. Figure 67 shows the different controls to the
AD9208 clock inputs. The output of the divider offers a 50%
duty cycle, high slew rate (fast edge) clock signal to the internal
ADC. See the Memory Map section for more details on using
this feature.
Input Clock Divider
The AD9208 contains an input clock divider with the ability to
divide the input clock by 1, 2, or 4. Select the divider ratios
using Register 0x0108 (see Figure 67).
The maximum frequency at the CLK± inputs is 6 GHz, which is
the limit of the divider. In applications where the clock input is
a multiple of the sample clock, take care to program the appropriate
divider ratio into the clock divider before applying the clock
signal; this ensures that the current transients during device
startup are controlled.
REG 0x011C,
0x011E
REG 0x0108
CLK+
CLK–
÷2
÷4
15547-062
Figure 67. Clock Divider Circuit
The AD9208 clock divider can be synchronized using the
external SYSREF± input. A valid SYSREF± signal causes the
clock divider to reset to a programmable state. This synchro-
nization feature allows multiple devices to have their clock
dividers aligned to guarantee simultaneous input sampling. See
the Memory Map Register Details section for more information.
Input Clock Divider ½ Period Delay Adjust
The input clock divider in the AD9208 provides phase delay in
increments of ½ the input clock cycle. Program Register 0x0109
to enable this delay independently for each channel. Changing
this register does not affect the stability of the JESD204B link.
Clock Fine Delay and Superfine Delay Adjust
Adjust the AD9208 sampling edge instant by writing to
Register 0x0110, Register 0x0111, and Register 0x0112. Bits[2:0]
of Register 0x0110 enable the selection of the fine delay, or the
fine delay with superfine delay. The fine delay allows the user to
delay the clock edges with 16 step or 192 step delay options. The
superfine delay is an unsigned control to adjust the clock delay
in superfine steps of 0.25 ps each.
Register 0x0112, Bits[7:0] offer the user the option to delay
the clock in 192 delay steps. Register 0x0111, Bits[7:0] offer the
user the option to delay the clock in 128 superfine steps. These
values can be programmed individually for each channel. To
use the superfine delay option, set the clock delay control in
Register 0x0110, Bits[2:0] to 0x2 or 0x6. Figure 68 shows the
controls available to the clock dividers within AD9208. It is
recommended to apply the same delay settings to the digital
delay circuits as are applied to the analog delay circuits to
maintain sample accuracy through the pipe.
PHASE
CH. B
PHASE
CH. A
CLK_DIV
0x0108
0x0109 FINE DELAY
0x0110,
0x0111,
0x0112 CHANNEL B
CHANNEL A
CLK INPUT
15547-063
Figure 68. Clock Divider Phase and Delay Controls
The clock delay adjustment takes effect immediately when it is
enabled via SPI writes. Enabling the clock fine delay adjust in
Register 0x0110 causes a datapath reset. However, the contents
of Register 0x0111 and Register 0x0112 can be changed without
affecting the stability of the JESD204B link.
Clock Coupling Considerations
The AD9208 has many different domains within the analog
supply that control various aspects of the data conversion. The
clock domain is supplied by Pin A4, Pin A5, Pin A10, Pin A11,
Pin B4, and Pin B11 on the analog supply, AVDD1 (0.975 V)
and Pin A6, Pin A9, Pin B6, Pin B7, Pin B8, Pin B9, Pin C6,
Pin C7, Pin C8, Pin C9, Pin D7, and Pin D8 on the ground
(AGND) side. To minimize coupling between the clock supply
domain and the other analog domains, it is recommended to
add a supply Q factor reduction circuitry (de-Q) for Pin A4 and
Pin A11, as well as Pin B4 and Pin B11, as shown in Figure 69.
Data Sheet AD9208
Rev. 0 | Page 31 of 136
A4 B4
100nF
10
FERRITE BEAD
220 AT
100MHz
DCR 0.5
A11 B11
AVDD1
PLANE
100nF
10
FERRITE BEAD
220 AT
100MHz
DCR 0.5
15547-064
Figure 69. De-Q Network Recommendation for the Clock Domain Supply
Clock Jitter Considerations
High speed, high resolution ADCs are sensitive to the quality of
the clock input. Calculate the degradation in SNR at a given
input frequency (fA) due only to aperture jitter (tJ) by
SNRJITTER = -20 × log10 (2 × π × fA × tJ)
In this equation, the rms aperture jitter represents the root
mean square of all jitter sources, including the clock input,
analog input signal, and ADC aperture jitter specifications.
IF undersampling applications are particularly sensitive to jitter
(see Figure 70).
130
120
110
100
90
80
70
60
50
40
30
10 100 1000 10000
SNR (dB)
ANALOG INPUT FREQUENCY (MHz)
12.5
f
S
25
f
S
50
f
S
100
f
S
200
f
S
400
f
S
800
f
S
15547-065
Figure 70. Ideal SNR vs. Input Frequency and Jitter
Treat the clock input as an analog signal when aperture jitter
may affect the dynamic range of the AD9208. Separate power
supplies for clock drivers from the ADC output driver supplies
to avoid modulating the clock signal with digital noise. If the
clock is generated from another type of source (by gating,
dividing, or other methods), retime the clock by the original clock
at the last step. Refer to the AN-501 Application Note and the
AN-756 Application Note for more in depth information about
jitter performance as it relates to ADCs.
Figure 71 shows the estimated SNR of the AD9208 across input
frequency for different clock induced jitter values. Estimate the
SNR by using the following equation:
SNR (dBFS) = −10log10
10
10 1010
JITTER
ADC SNR
SNR
61
45
47
49
51
53
55
57
59
100 1000 10000
SNR (dBFS)
INPUT FREQUENCY (MHz)
25fS
50fS
75fS
100fS
125fS
150fS
175fS
200fS
15547-066
Figure 71. Estimated SNR Degradation for the AD9208 vs. Input Frequency
and RMS Jitter
POWER-DOWN/STANDBY MODE
The AD9208 has a PDWN/STBY pin that can be used to
configure the device in power-down or standby mode. The
default operation is PDWN. The PDWN/STBY pin is a logic
high pin. When in power-down mode, the JESD204B link is
disrupted. The power-down option can also be set via
Register 0x003F and Register 0x0040.
In standby mode, the JESD204B link is not disrupted and transmits
zeros for all converter samples. Change this transmission using
Register 0x0571, Bit 7 to select /K/ characters.
TEMPERATURE DIODE
The AD9208 contains diode-based temperature sensors. The
diodes output voltages commensurate to the temperature of the
silicon. There are multiple diodes on the die, but the results
established using the temperature diode at the central location
of the die can be regarded as representative of the entire die.
However, in applications where only one channel is used (the
other channel being in a power-down state), it is recommended
to read the temperature diode corresponding to the channel
that is on. The Figure 72 shows the locations of the diodes in
the AD9208 with voltages that can be output to the VREF pin.
In each location, there is a pair of diodes, one of which is 20×
the size of the other. It is recommended to use both diodes in a
location to obtain an accurate estimate of the die temperature.
For more information, see the AN-1432 Application Note, Practical
Thermal Modeling and Measurements in High Power ICs.
AD9208 Data Sheet
Rev. 0 | Page 32 of 136
ADC
AADC
B
ADC
DIGITAL
VREF
JESD204B DRIVER
TEMPERAT URE DIODE
LOCATIONS
CHANNEL A, CEN TRAL ,
CHANNEL B
15547-067
Figure 72. Temperature Diode Locations in the Die
The temperature diode voltages can be exported to the VREF pin
using the SPI. Use Register 0x18E6 to enable or disable diodes.
It is important to note that other voltages may be exported to
the VREF pin at the same time, which can result in undefined
behavior. To ensure a proper readout, switch off all other voltage
exporting circuits as described in this section. Figure 73 shows
the block diagram of the controls that are required to enable the
diode voltage readout.
TEMPERAT URE DIODE
LOCATION SELECT
SPI REGISTER (0x18E6)
VREF PIN
CONTROL
SPI REGISTER
(0x18A6)
CHANNE L A
CENTRAL
V
REF CHAN NEL B
15547-068
Figure 73. Register Controls to Output Temperature Diode Voltage on the
VREF Pin
The SPI writes required to export the central temperature diode
are as follows (see Table 46 for more information):
1. Set Register 0x0008 to 0x03 to select both channels.
2. Set Register 0x18E3 to 0x00 to turn off VCM export.
3. Set Register 0x18A6 to 0x00 to turn off voltage reference
export.
4. Set Register 0x18E6 to 0x01 to turn on voltage export of
the central 1× temperature diode. The typical voltage
response of the temperature diode is shown in Figure 74.
Although this voltage represents the die temperature, it is
recommended to take measurements from a pair of diodes
for improved accuracy. The following step explains how to
enable the 20× diode.
5. Set Register 0x18E6 to 0x02 to turn on the second central
temperature diode of the pair, which is 20× the size of the
first. For the method using two diodes simultaneously to
achieve a more accurate result, see the AN-1432 Application
Note, Practical Thermal Modeling and Measurements in
High Power ICs.
0.80
0.75
0.70
0.65
0.60
0.55
0.50
–40 –20 0 20
JUNCTIO N T E M P E RAT URE (°C)
TE M P E R ATURE DIOD E V OL TAG E ( V )
40 60 80 100
15547-069
Figure 74. Typical Voltage Response of the 1× Temperature Diode
The relationship between the measured delta voltage (ΔV) and
the junction temperature in °C is shown in Figure 75.
150
–40
–30
–20
–10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
60 65 70 75 80 85 90 95 100 105 110
DELTA VOLTAGE (mV)
T
J
(°C)
15547-070
Figure 75. Junction Temperature vs. ΔV (mV)
Data Sheet AD9208
Rev. 0 | Page 33 of 136
ADC OVERRANGE AND FAST DETECT
In receiver applications, it is desirable to have a mechanism to
reliably determine when the converter is about to be clipped.
The standard overrange bit in the JESD204B outputs provides
information on the state of the analog input that is of limited
usefulness. Therefore, it is helpful to have a programmable
threshold below full scale that allows time to reduce the gain
before the clip actually occurs. In addition, because input
signals can have significant slew rates, the latency of this
function is of major concern. Highly pipelined converters can
have significant latency. The AD9208 contains fast detect
circuitry for individual channels to monitor the threshold and
assert the FD_A and FD_B pins.
ADC OVERRANGE
The ADC overrange indicator is asserted when an overrange is
detected on the input of the ADC. The overrange indicator can
be embedded within the JESD204B link as a control bit (when
CSB > 0). The latency of this overrange indicator matches the
sample latency.
The AD9208 also records any overrange condition in any of the
eight virtual converters. For more information on the virtual
converters, refer to Figure 84. The overrange status of each virtual
converter is registered as a sticky bit in Register 0x0563. The
contents of Register 0x0563 can be cleared using Register 0x0562,
by toggling the bits corresponding to the virtual converter to set
and reset position.
FAST THRESHOLD DETECTION (FD_A AND FD_B)
The FD_A or FD_B pin is immediately set whenever the
absolute value of the input signal exceeds the programmable
upper threshold level. The FD bit is only cleared when the
absolute value of the input signal drops below the lower
threshold level for greater than the programmable dwell time.
This feature provides hysteresis and prevents the FD bit from
excessively toggling.
The operation of the upper threshold and lower threshold
registers, along with the dwell time registers, is shown in
Figure 76.
The FD indicator is asserted if the input magnitude exceeds the
value programmed in the fast detect upper threshold registers,
located at Register 0x0247 and Register 0x0248. The selected
threshold register is compared with the signal magnitude at the
output of the ADC. The fast upper threshold detection has a
latency of 28 clock cycles (maximum). The approximate upper
threshold magnitude is defined by
Upper Threshold Magnitude (dBFS) = 20log(Threshold
Magnitude/213)
The FD indicators are not cleared until the signal drops below
the lower threshold for the programmed dwell time. The lower
threshold is programmed in the fast detect lower threshold
registers, located at Register 0x0249 and Register 0x024A. The
fast detect lower threshold register is a 13-bit register that is
compared with the signal magnitude at the output of the ADC.
This comparison is subject to the ADC pipeline latency, but is
accurate in terms of converter resolution. The lower threshold
magnitude is defined by
Lower Threshold Magnitude (dBFS) = 20log(Threshold
Magnitude/213)
For example, to set an upper threshold of −6 dBFS, write 0xFFF
to Register 0x0247 and Register 0x0248. To set a lower threshold of
−10 dBFS, write 0xA1D to Register 0x0249 and Register 0x024A.
The dwell time can be programmed from 1 to 65,535 sample
clock cycles by placing the desired value in the fast detect dwell
time registers, located at Register 0x024B and Register 0x024C.
See Register 0x0040 and Register 0x0245 to Register 0x024C in
the Memory Map section (see Table 46) for more details.
UPPER THRESHOLD
LOWER THRESHOLD
FD_A OR FD_B
MIDSCALE
DWELL TIME
TIMER RESET BY
RISE ABOVE
LOWER
THRESHOLD
TIMER COMPLETES BEFORE
SIGNAL RISES ABOVE
LOWER THRESHOLD
DWELL TIME
15547-071
Figure 76. Threshold Settings for the FD_A and FD_B Signals
AD9208 Data Sheet
Rev. 0 | Page 34 of 136
ADC APPLICATION MODES AND JESD204B Tx CONVERTER MAPPING
The AD9208 contains a configurable signal path that allows
different features to be enabled for different applications. These
features are controlled using the chip application mode register,
Register 0x0200. The chip operating mode is controlled by Bits[3:0]
in this register, and the chip Q ignore is controlled by Bit 5.
The AD9208 contains the following modes:
Full bandwidth mode: two 14-bit ADC cores running at
full sample rate.
DDC mode: up to four digital downconverter (DDC)
channels.
After the chip application mode is selected, the output
decimation ratio is set using the chip decimation ratio in
Register 0x0201, Bits[3:0]. The output sample rate = ADC
sample rate/the chip decimation ratio.
To support the different application layer modes, the AD9208
treats each sample stream (real, I, or Q) as originating from
separate virtual converters.
Table 11 shows the number of virtual converters required and
the transport layer mapping when channel swapping is disabled.
Figure 77 shows the virtual converters and their relationship to
the DDC outputs when complex outputs are used.
Each DDC channel outputs either two sample streams (I/Q) for
the complex data components (real + imaginary), or one sample
stream for real (I) data. The AD9208 can be configured to use up to
eight virtual converters, depending on the DDC configuration.
The I/Q samples are always mapped in pairs with the I samples
mapped to the first virtual converter and the Q samples mapped
to the second virtual converter. With this transport layer mapping,
the number of virtual converters are the same whether a single
real converter is used along with a digital downconverter block
producing I/Q outputs, or whether an analog downconversion
is used with two real converters producing I/Q outputs.
Figure 78 shows a block diagram of the two scenarios described
for I/Q transport layer mapping.
Table 11. Virtual Converter Mapping
Number of
Virtual
Converters
Supported
Chip Operating
Mode
(Reg. 0x0200,
Bits[3:0])
Chip Q Ignore
(0x0200, Bit 5)
Virtual Converter Mapping
0 1 2 3 4 5 6 7
1 to 2 Full bandwidth
mode (0x0)
Real or
complex (0x0)
ADC A
samples
ADC B
samples
Unused Unused Unused Unused Unused Unused
1 One DDC mode
(0x1)
Real (I only)
(0x1)
DDC0 I
samples
Unused Unused Unused Unused Unused Unused Unused
2 One DDC mode
(0x1)
Complex (I/Q)
(0x0)
DDC0 I
samples
DDC0 Q
samples
Unused Unused Unused Unused Unused Unused
2 Two DDC mode
(0x2)
Real (I only)
(0x1)
DDC0 I
samples
DDC1 I
samples
Unused Unused Unused Unused Unused Unused
4 Two DDC mode
(0x2)
Complex (I/Q)
(0x0)
DDC0 I
samples
DDC0 Q
samples
DDC1 I
samples
DDC1 Q
samples
Unused Unused Unused Unused
4 Four DDC mode
(0x3)
Real (I only)
(0x1)
DDC0 I
samples
DDC1 I
samples
DDC2 I
samples
DDC3 I
samples
Unused Unused Unused Unused
8 Four DDC mode
(0x3)
Complex (I/Q)
(0x0)
DDC0 I
samples
DDC0 Q
samples
DDC1 I
samples
DDC1 Q
samples
DDC2 I
samples
DDC2 Q
samples
DDC3 I
samples
DDC3 Q
samples
DDC 3
OUTPUT
INTERFACE
I/Q
CROSSBAR
MUX
I
Q
I
QQ
CONVERTER 7
REAL/I
CONVERTER 6
REAL/Q
REAL/I
DDC 2
I
Q
I
QQ
CONVERTER 5
REAL/I
CONVERTER 4
REAL/Q
REAL/I
DDC 1
I
Q
I
QQ
CONVERTER 3
REAL/I
CONVERTER 2
REAL/Q
REAL/I
DDC 0
I
Q
I
QQ
CONVERTER 1
REAL/I
CONVERTER 0
REAL/Q
REAL/I
REAL/I ADC A
SAMPLING
AT
fS
REAL/Q ADC B
SAMPLING
AT
fS
15547-072
Figure 77. DDCs and Virtual Converter Mapping
Data Sheet AD9208
Rev. 0 | Page 35 of 136
JESD204B
Tx
90°
PHASE
Q
CONVERTER 1
I
CONVERTER 0
IADC
ADC
Q
REAL
REAL
REAL
L LANES
JESD204B
Tx
DIGITAL
DOWN
CONVERSION
Q
CONVERTER 1
I
CONVERTER 0
L LANES
I/Q ANALOG MIXING
M = 2
DIGITAL DOWNCONVERSION
M = 2
ADC
15547-073
Figure 78. I/Q Transport Layer Mapping
AD9208 Data Sheet
Rev. 0 | Page 36 of 136
PROGRAMMABLE FIR FILTERS
SUPPORTED MODES
The AD9208 supports the following modes of operation (the
asterisk symbol (*) denotes convolution):
Real 48-tap filter for each I/Q channel (see Figure 79)
DOUT_I[n] = DIN_I[n] * XY_I[n]
DOUT_Q[n] = DIN_Q[n] * XY_Q[n]
Real 96-tap filter for on either I or Q channel (see Figure 80)
DOUT_I[n] = DIN_I[n] * XY_I[n]
DOUT_Q[n] = DIN_Q[n] * XY_Q[n]
Real set of two cascaded 24-tap filters for each I/Q channel
(see Figure 81)
DOUT_I[n] = DIN_I[n] * X_I[n] * Y_I[n]
DOUT_Q[n] = DIN_Q[n] * X_Q[n] * Y_Q[n]
Half complex filter using two real 48-tap filters for the I/Q
channels (see Figure 82)
DOUT_I[n] = DIN_I[n]
DOUT_Q[n] = DIN_Q[n] * XY_Q[n] + DIN_I[n] *
XY_I[n]
Full complex filter using four real 24-tap filters for the I/Q
channels (see Figure 83)
DOUT_I[n] = DIN_I[n] * X_I[n] + DIN_Q[n] *
Y_Q[n]
DOUT_Q[n] = DIN_Q[n] * X_Q[n] + DIN_I[n] *
Y_I[n]
ADC B
CORE
Q (IMAG) 48-TAP FIR
FILTER
xy
Q
[n]
DIN
Q
[n] DOUT
Q
[n]
ADC A
CORE
I (REAL) 48-TAP FIR
FILTER
xy
I
[n]
DIN
I
[n] DOUT
I
[n] I (REAL)
PROGRAMMABLE FILTER (PFILT)
Q (IMAG)
SIGNAL
PROCESSING
BLOCKS
JESD204B
INTERFACE
15547-074
Figure 79. Real 48-Tap Filter Configuration
ADC B
CORE
Q (IMAG) DIN
Q
[n] DOUT
Q
[n]
ADC A
CORE
I (REAL) 96-TAP FIR
FILTER
x
I
y
I
x
Q
y
Q
[n]
DIN
I
[n] DOUT
I
[n] I (REAL)
PROGRAMMABLE FILTER (PFILT)
Q (IMAG)
SIGNAL
PROCESSING
BLOCKS
JESD204B
INTERFACE
15547-075
Figure 80. Real 96-Tap Filter Configuration
Data Sheet AD9208
Rev. 0 | Page 37 of 136
ADC B
CORE
Q (IMAG) DINQ [n]
DOUTQ [n]
ADC A
CORE
I (REAL) 24-TAP FIR
FILTER
xI [n]
24-TAP FIR
FILTER
yI [n]
24-TAP FIR
FILTER
yQ [n]
24-TAP FIR
FILTER
xQ[n]
DINI [n] DOUTI [n] I (REAL)
PROGRAMMABLE FILTER (PFILT)
Q (IMAG)
SIGNAL
PROCESSING
BLOCKS
JESD204B
INTERFACE
15547-076
Figure 81. Real, Two Cascaded, 24-Tap Filter Configuration
ADC B
CORE
Q (IMAG) DINQ [n] DOUTQ [n]
+
+
ADC A
CORE
I (REAL) 0 TO 47
DELAY TAPS
48-TAP FIR
FILTER
xyI [n]
48-TAP FIR
FILTER
xyQ[n]
DINI [n] DOUTI [n] I (REAL)
PROGRAMMABLE FILTER (PFILT)
Q (IMAG)
SIGNAL
PROCESSING
BLOCKS
JESD204B
INTERFACE
15547-077
Figure 82. 48-Tap Half Complex Filter Configuration
ADC B
CORE
Q (IMAG)
DINQ [n]
DOUTQ [n]
+
+
+
+
ADC A
CORE
I (REAL) 24-TAP FIR
FILTER
xI [n]
24-TAP FIR
FILTER
yI [n]
24-TAP FIR
FILTER
yQ [n]
24-TAP FIR
FILTER
xQ[n]
DINI [n] DOUTI [n] I (REAL)
PROGRAMMABLE FILTER (PFILT)
Q (IMAG)
SIGNAL
PROCESSING
BLOCKS
JESD204B
INTERFACE
15547-078
Figure 83. 24-Tap Full Complex Filter Configuration.
AD9208 Data Sheet
Rev. 0 | Page 38 of 136
PROGRAMMING INSTRUCTIONS
Use the following procedure to set up the programmable FIR filter:
1. Enable the sample clock to the device.
2. Configure the mode registers as follows:
a. Set the device index to Channel A (I path)
(Register 0x0008 = 0x01).
b. Set the I path mode (I mode) and gain in
Register 0x0DF8 and Register 0x0DF9 (see Table 12
and Table 13).
c. Set the device index to Channel B (Q path)
(Register 0x0008 = 0x02).
d. Set the Q path mode (Q mode) and gain in
Register 0x0DF8 and Register 0x0DF9.
3. Wait at least 5 µs to allow the programmable filter to power up.
4. Program the I path coefficients to the internal shadow
registers as follows:
a. Set the device index to Channel A (I path)
(Register 0x0008 = 0x01).
b. Program the XI coefficients in Register 0x0E00 to
Register 0x0E2F (see Table 14 and Table 15).
c. Program the YI coefficients in Register 0x0F00 to
Register 0x0F2F (see Table 14 and Table 15).
d. Program the tapped delay in Register 0x0F30 (note
that this step is optional).
5. Program the Q path coefficients to the internal shadow
registers as follows:
a. Set the device index to Channel B (Q path)
(Register 0x0008 = 0x02).
b. Set the Q path mode and gain in Register 0x0DF8 and
Register 0x0DF9 (see Table 12 and Table 13).
c. Program the XQ coefficients in Register 0x0E00 to
Register 0x0E2F (see Table 14 and Table 15)
d. Program the YQ coefficients in Register 0x0F00 to
Register 0x0F2F (see Table 14 and Table 15)
e. Program the tapped delay in Register 0x0F30 (note
that this step is optional).
6. Set the chip transfer bit using either of the following
methods (note that setting the chip transfer bit applies the
programmed shadow coefficients to the filter):
a. Via the register map using the write the chip transfer
bit (Register 0x000F = 0x01).
b. Via a GPIO pin, as follows:
i. Configure one of the GPIO pins as the chip
transfer bit in Register 0x0040 to Register 0x0042.
ii. Toggle the GPIO pin to initiate the chip transfer
(the rising edge is triggered).
7. When the I or Q path mode register changes in
Register 0x0DF8, all coefficients must be reprogrammed.
Table 12. Register 0x0DF8 Definition
Bit(s) Description
[7:3] Reserved
[2:0] Filter mode (I mode or Q mode)
000: filters bypassed
001: real 24-tap filter (X only)
010: real 48-tap filter (X and Y together)
100: real set of two cascaded 24-tap filters (X then Y
cascaded)
101: full complex filter using four real 24-tap filters for the
A/B channels (opposite channel must also be set to 101)
110: half complex filter using two real 48-tap filters +
48-tap delay line (X and Y together) (opposite channel
must also be set to 010)
111: real 96-tap filter (XI, YI, XQ, and YQ together)
(opposite channel must be set to 000)
Table 13. Register 0x0DF9 Definition
Bit(s) Description
7 Reserved
[6:4] Y filter gain
110: −12 dB loss
111: −6 dB loss
000: 0 dB gain
001: 6 dB gain
010: 12 dB gain
3 Reserved
[2:0] X filter gain
110: −12 dB loss
111: −6 dB loss
000: 0 dB gain
001: 6 dB gain
010: 12 dB gain
Table 14 and Table 15 show the coefficient tables in
Register 0x0E00 to Register 0x0F30. Note that all coefficients
are Q1.15 format (sign bit + 15 fractional bits).
Data Sheet AD9208
Rev. 0 | Page 39 of 136
Table 14. I Coefficient Table (Device Selection = 0x1)1
Addr.
Single 24-Tap
Filter (I Mode
[2:0] = 0x1)
Single 48-Tap
Filter (I Mode
[2:0] = 0x2)
Two Cascaded
24-Tap Filters (I
Mode [2:0] = 0x4)
Full Complex
24-Tap Filters (I
Mode [2:0] = 0x5
and Q Mode
[2:0] = 0x5)
Half Complex
48-Tap Filters (I
Mode [2:0] = 0x6
and Q Mode
[2:0] = 0x2)2
I Path 96-Tap
Filter (I Mode[2:0] =
0x7 and Q Mode
[2:0] = 0x0)3
Q Path 96-Tap
Filter (I Mode
[2:0] = 0x0 and Q
Mode [2:0] = 0x7)3
0x0E00 XI C0 [7:0] XI C0 [7:0] XI C0 [7:0] XI C0 [7:0] XI C0 [7:0] XI C0 [7:0] XQ C48 [7:0]
0x0E01 XI C0 [15:8] XI C0 [15:8] XI C0 [15:8] XI C0 [15:8] XI C0 [15:8] XI C0 [15:8] XQ C48 [15:8]
0x0E02 XI C1 [7:0] XI C1 [7:0] XI C1 [7:0] XI C1 [7:0] XI C1 [7:0] XI C1 [7:0] XQ C49 [7:0]
0x0E03 XI C1 [15:8] XI C1 [15:8] XI C1 [15:8] XI C1 [15:8] XI C1 [15:8] XI C1 [15:8] XQ C49 [15:8]
… … … … … … … …
0x0E2E XI C23 [7:0] XI C23 [7:0] XI C23 [7:0] XI C23 [7:0] XI C23 [7:0] XI C23 [7:0] XQ C71 [7:0]
0x0E2F XI C23 [15:0] XI C23 [15:0] XI C23 [15:0] XI C23 [15:0] XI C23 [15:0] XI C23 [15:0] XQ C71 [15:0]
0x0F00 Unused YI C24 [7:0] YI C0 [7:0] YI C0 [7:0] YI C24 [7:0] YI C24 [7:0] YQ C72 [7:0]
0x0F01 Unused YI C24 [15:8] YI C0 [15:8] YI C0 [15:8] YI C24 [15:8] YI C24 [15:8] YQ C72 [15:8]
0x0F02 Unused YI C25 [7:0] YI C1 [7:0] YI C1 [7:0] YI C25 [7:0] YI C25 [7:0] YQ C73 [7:0]
0x0F03 Unused YI C25 [15:8] YI C1 [15:8] YI C1 [15:8] YI C25 [15:8] YI C25 [15:8] YQ C73 [15:8]
… … … … … … … …
0x0F2E Unused YI C47 [7:0] YI C23 [7:0] YI C23 [7:0] YI C47 [7:0] YI C47 [7:0] YQ C95 [7:0]
0x0F2F Unused YI C47 [15:0] YI C23 [15:0] YI C23 [15:0] YI C47 [15:0] YI C47 [15:0] YQ C95 [15:0]
0x0F30 Unused Unused Unused Unused I path tapped delay Unused Unused
0: 0 tapped delay
(matches C0 in the
filter)
1: 1 tapped delays
…
47: 47 tapped delays
1 XI Cn means I Path X Coefficient n. YI Cn means I Path Y Coefficient n.
2 When using the I path in half-complex 48-tap filter mode, the Q path must be in single 48-tap filter mode.
3 When using the I path in 96-tap filter mode, the Q path must be in bypass mode.
Table 15. Q Coefficient Table (Device Selection = 0x2)1
Addr.
Single 24-Tap
Filter (Q Mode
[2:0] = 0x1)
Single 48-Tap
Filter (Q Mode
[2:0] = 0x2)
Two Cascaded
24-Tap Filters (Q
Mode [2:0] = 0x4)
Full Complex
24-Tap Filters (Q
Mode [2:0] = 0x5
and I Mode
[2:0] = 0x5)
Half Complex
48-Tap Filters (Q
Mode [2:0] = 0x6
and I Mode
[2:0] = 0x2)2
I Path 96-Tap
Filter (Q Mode
[2:0] = 0x0 and I
Mode [2:0] = 0x7)3
Q Path 96-Tap
Filter (Q Mode
[2:0] = 0x7 and I
Mode [2:0] = 0x0)3
0x0E00 XQ C0 [7:0] XQ C0 [7:0] XQ C0 [7:0] XQ C0 [7:0] XQ C0 [7:0] XI C48 [7:0] XQ C0 [7:0]
0x0E01 XQ C0 [15:8] XQ C0 [15:8] XQ C0 [15:8] XQ C0 [15:8] XQ C0 [15:8] XI C48 [15:8] XQ C0 [15:8]
0x0E02 XQ C1 [7:0] XQ C1 [7:0] XQ C1 [7:0] XQ C1 [7:0] XQ C1 [7:0] XI C49 [7:0] XQ C1 [7:0]
0x0E03 XQ C1 [15:8] XQ C1 [15:8] XQ C1 [15:8] XQ C1 [15:8] XQ C1 [15:8] XI C49 [15:8] XQ C1 [15:8]
… … … … … … … …
0x0E2E XQ C23 [7:0] XQ C23 [7:0] XQ C23 [7:0] XQ C23 [7:0] XQ C23 [7:0] XI C71 [7:0] XQ C23 [7:0]
0x0E2F XQ C23 [15:0] XQ C23 [15:0] XQ C23 [15:0] XQ C23 [15:0] XQ C23 [15:0] XI C71 [15:0] XQ C23 [15:0]
0x0F00 Unused YQ C24 [7:0] YQ C0 [7:0] YQ C0 [7:0] YQ C24 [7:0] YI C72 [7:0] YQ C24 [7:0]
0x0F01 Unused YQ C24 [15:8] YQ C0 [15:8] YQ C0 [15:8] YQ C24 [15:8] YI C72 [15:8] YQ C24 [15:8]
0x0F02 Unused YQ C25 [7:0] YQ C1 [7:0] YQ C1 [7:0] YQ C25 [7:0] YI C73 [7:0] YQ C25 [7:0]
0x0F03 Unused YQ C25 [15:8] YQ C1 [15:8] YQ C1 [15:8] YQ C25 [15:8] YI C73 [15:8] YQ C25 [15:8]
… … … … … … … …
0x0F2E Unused YQ C47 [7:0] YQ C23 [7:0] YQ C23 [7:0] YQ C47 [7:0] YI C95 [7:0] YQ C47 [7:0]
0x0F2F Unused YQ C47 [15:0] YQ C23 [15:0] YQ C23 [15:0] YQ C47 [15:0] YI C95 [15:0] YQ C47 [15:0]
0x0F30 Unused Unused Unused Unused
Q Path Tapped
Delay
Unused Unused
0: 0 tapped delay
(matches C0 in the
filter)
1: 1 tapped delays
…
47: 47 tapped
delays
1 XQ Cn means Q Path X Coefficient n. YQ Cn means Q Path Y Coefficient n.
2 When using the I path in half-complex 48-tap filter mode, the Q path must be in single 48-tap filter mode.
3 When using the I path in 96-tap filter mode, the Q path must be in bypass mode.
AD9208 Data Sheet
Rev. 0 | Page 40 of 136
DIGITAL DOWNCONVERTER (DDC)
The AD9208 includes four digital downconverters (DDC0 to
DDC3) that provide filtering and reduce the output data rate.
This digital processing section includes an NCO, multiple
decimating FIR filters, a gain stage, and a complex to real
conversion stage. Each of these processing blocks has control lines
that allow it to be independently enabled and disabled to provide
the desired processing function. The digital downconverter can be
configured to output either real data or complex output data.
The DDCs output a 16-bit stream. To enable this operation, the
converter number of bits, N, is set to a default value of 16, even
though the analog core only outputs 14 bits. In full bandwidth
operation, the ADC outputs are the 14-bit word followed by two
zeros, unless the tail bits are enabled.
DDC I/Q INPUT SELECTION
The AD9208 has two ADC channels and four DDC channels.
Each DDC channel has two input ports that can be paired to
support both real and complex inputs through the I/Q crossbar
mux. For real signals, both DDC input ports must select the
same ADC channel (that is, DDC Input Port I = ADC Channel A
and DDC Input Port Q = ADC Channel A). For complex
signals, each DDC input port must select different ADC
channels (that is, DDC Input Port I = ADC Channel A and
DDC Input Port Q = ADC Channel B).
The inputs to each DDC are controlled by the DDC input selec-
tion registers (Register 0x0311, Register 0x0331, Register 0x0351,
and Register 0x0371). See Table 46 for information on how to
configure the DDCs.
DDC I/Q OUTPUT SELECTION
Each DDC channel has two output ports that can be paired to
support both real and complex outputs. For real output signals,
only the DDC Output Port I is used (the DDC Output Port Q is
invalid). For complex I/Q output signals, both DDC Output
Port I and DDC Output Port Q are used.
The I/Q outputs to each DDC channel are controlled by the
DDC complex to real enable bit, Bit 3, in the DDC control
registers (Register 0x0310, Register 0x0330, Register 0x0350,
and Register 0x0370).
The chip Q ignore bit in the chip mode register (Register 0x0200,
Bit 5) controls the chip output muxing of all the DDC channels.
When all DDC channels use real outputs, set this bit high to
ignore all DDC Q output ports. When any of the DDC channels
are set to use complex I/Q outputs, the user must clear this bit
to use both DDC Output Port I and DDC Output Port Q. For
more information, see Figure 101.
DDC GENERAL DESCRIPTION
The four DDC blocks are used to extract a portion of the full
digital spectrum captured by the ADC(s). They are intended for
IF sampling or oversampled baseband radios requiring wide
bandwidth input signals.
Each DDC block contains the following signal processing
stages:
Frequency translation stage (optional)
Filtering stage
Gain stage (optional)
Complex to real conversion stage (optional)
DDC Frequency Translation Stage (Optional)
This stage consists of a phase coherent NCO and quadrature
mixers that can be used for frequency translation of both real or
complex input signals. The phase coherent NCO allows an
infinite number of frequency hops that are all referenced back
to a single synchronization event. It also includes 16 shadow
registers for fast switching applications. This stage shifts a
portion of the available digital spectrum down to baseband.
DDC Filtering Stage
After shifting down to baseband, this stage decimates the
frequency spectrum using multiple low-pass finite impulse
response (FIR) filters for rate conversion. The decimation
process lowers the output data rate, which in turn reduces the
output interface rate.
DDC Gain Stage (Optional)
Because of losses associated with mixing a real input signal
down to baseband, this stage compensates by adding an
additional 0 dB or 6 dB of gain.
DDC Complex to Real Conversion Stage (Optional)
When real outputs are necessary, this stage converts the
complex outputs back to real by performing an fS/4 mixing
operation plus a filter to remove the complex component of the
signal.
Figure 84 shows the detailed block diagram of the DDCs
implemented in the AD9208.
Figure 85 shows an example usage of one of the four DDC
channels with a real input signal and four half-band filters
(HB4 + HB3 + HB2 + HB1) used. It shows both complex
(decimate by 16) and real (decimate by 8) output options.
Data Sheet AD9208
Rev. 0 | Page 41 of 136
NCO
+
MIXER
(OPTIONAL)
DECIMATION
FILTERS
REAL/I
DDC 0
I
REAL/I Q
REAL/I
CONVERTER 0
Q CONVERTER 1
GAIN = 0 OR +6dB
COMPLEX TO REAL
CONVERSION (OPTIONAL)
NCO
+
MIXER
(OPTIONAL)
DECIMATION
FILTERS
REAL/I
JESD204B TRANSMIT INTERFACE
DDC 1
I
REAL/I Q
REAL/I
CONVERTER 2
Q CONVERTER 3
L
JESD204B
LANES
AT UP TO
16Gbps
GAIN = 0 OR +6dB
COMPLEX TO REAL
CONVERSION (OPTIONAL)
NCO
+
MIXER
(OPTIONAL)
DECIMATION
FILTERS
REAL/I
DDC 2
I
REAL/I Q
REAL/I
CONVERTER 4
Q CONVERTER 5
GAIN = 0 OR +6dB
COMPLEX TO REAL
CONVERSION (OPTIONAL)
NCO
+
MIXER
(OPTIONAL)
SYNCHRONIZATION
CONTROL CIRCUITS
SYSREF
PIN SYSREF SYSREF
REGISTER MAP
CONTROLS
GPIO PINS
NCO CHANNEL
SELECTION
CIRCUITS
NCO CHANNEL SELECTION
DCM = DECIMATION
DECIMATION
FILTERS
REAL/I
DDC 3
I
REAL/I Q
REAL/I
CONVERTER 6
Q CONVERTER 7
GAIN = 0 OR +6dB
COMPLEX TO REAL
CONVERSION (OPTIONAL)
ADC B
SAMPLING
AT
f
S
REAL/Q
ADC A
SAMPLING
AT
f
S
REAL/I
I/Q CROSSBAR MUX
15547-079
Figure 84. DDC Detailed Block Diagram
AD9208 Data Sheet
Rev. 0 | Page 42 of 136
cos(t)
0°
90°
I
Q
REAL
BANDWIDTH OF
INTEREST
BANDWIDTH OF
INTEREST IMAGE
DIGITAL FILTER
RESPONSE
DC
DC
ADC
SAMPLING
AT
f
S
REAL REAL
HALF-
BAND
FILTER
HB4 FIR
2
HALF-
BAND
FILTER
HB3 FIR
2
HALF-
BAND
FILTER
HB2 FIR
2
HALF-
BAND
FILTER
HB1 FIR
I I
HALF-
BAND
FILTER
HB4 FIR
2
HALF-
BAND
FILTER
HB3 FIR
2
HALF-
BAND
FILTER
HB2 FIR
2
2
2
HALF-
BAND
FILTER
HB1 FIR
Q Q
ADC
REAL INPUT—SAMPLED AT
f
S
FILTERING STAGE
4 DIGITAL HALF-BAND FILTERS
(HB4 + HB3 + HB2 + HB1)
FREQUENCY TRANSLATION STAGE (OPTIONAL)
NCO TUNES CENTER OF
BANDWIDTH OF INTEREST
TO BASEBAND
BANDWIDTH OF
INTEREST IMAGE
(–6dB LOSS DUE TO
NCO + MIXER)
BANDWIDTH OF INTEREST
(–6dB LOSS DUE TO
NCO + MIXER)
–
f
S
/2 –
f
S
/3 –
f
S
/4 –
f
S
/8
f
S
/16
f
S
/8
f
S
/4
f
S
/3
f
S
/2–
f
S
/16
–
f
S
/32
f
S
/32
–
f
S
/2 –
f
S
/3 –
f
S
/4 –
f
S
/8
f
S
/16
f
S
/8
f
S
/4
f
S
/3
f
S
/2–
f
S
/16
–
f
S
/32
f
S
/32
–sin(t)
48-BIT
NCO
DC
DIGITAL FILTER
RESPONSE
DC
DC
I
Q
I
Q
2
2
I
Q
REAL/I
COMPLEX
TO
REAL
I
Q
GAIN STAGE (OPTIONAL)
0dB OR 6dB GAIN
GAIN STAGE (OPTIONAL)
0dB OR 6dB GAIN
COMPLEX (I/Q) OUTPUTS
DECIMATE BY 16
REAL (I) OUTPUTS
DECIMATE BY 8
COMPLEX TO REAL
CONVERSION STAGE (OPTIONAL)
f
S
/4 MIXING + COMPLEX FILTER TO REMOVE Q
–
f
S
/8
f
S
/16
f
S
/8–
f
S
/16
–
f
S
/32
f
S
/32
–
f
S
/8
f
S
/16
f
S
/8–
f
S
/16
–
f
S
/32
f
S
/32
f
S
/16–
f
S
/16
–
f
S
/32
f
S
/32
6dB GAIN TO
COMPENSATE FOR
NCO + MIXER LOSS
6dB GAIN TO
COMPENSATE FOR
NCO + MIXER LOSS
DOWNSAMPLE BY 2
+6dB
+6dB
+6dB
+6dB
DIGITAL MIXER + NCO
FOR
f
S
/3 TUNING, THE FREQUENCY TUNING WORD = ROUND
((
f
S
/3)/
f
S
× 2
48
) = +9.3825
13
(0x5555_5555_5555)
15547-080
Figure 85. DDC Theory of Operation Example (Real Input)
Data Sheet AD9208
Rev. 0 | Page 43 of 136
DDC FREQUENCY TRANSLATION
DDC Frequency Translation General Description
Frequency translation is accomplished by using a 48-bit
complex NCO with a digital quadrature mixer. This stage
translates either a real or complex input signal from an IF to a
baseband complex digital output (carrier frequency = 0 Hz).
The frequency translation stage of each DDC can be controlled
individually and supports four different IF modes using Bits[5:4]
of the DDC control registers (Register 0x0310, Register 0x0330,
Register 0x0350, and Register 0x0370). These IF modes are
Variable IF mode
0 Hz IF or zero IF (ZIF) mode
fS/4 Hz IF mode
Test mode
Variable IF Mode
In this mode, the NCO and mixers are enabled. NCO output
frequency can be used to digitally tune the IF frequency.
0 Hz IF (ZIF) Mode
In this mode, the mixers are bypassed, and the NCO is disabled.
fS/4 Hz IF Mode
In this mode, the mixers and the NCO are enabled in
downmixing by fS/4 mode to save power.
Test Mode
In this mode, input samples are forced to 0.999 to positive full
scale. The NCO is enabled. This test mode allows the NCOs to
directly drive the decimation filters.
Figure 86 and Figure 87 show examples of the frequency
translation stage for both real and complex inputs.
BANDWIDTH OF
INTEREST
BANDWIDTH OF
INTEREST IMAGE
NCO FREQUENCY TUNING WORD (FTW) SELECTION
48-BIT NCO FTW = MIXING FREQUENCY/ADC SAMPLE RATE × 4096
ADC + DIGITAL MIXER + NCO
REAL INPUT—SAMPLED AT
f
S
DC
DC
–
f
S
/32
f
S
/32
DC
–
f
S
/32
f
S
/32
cos(t)
0°
90°
I
Q
ADC
SAMPLING
AT
f
S
REAL REAL
–sin(t)
48-BIT
NCO
POSITIVE FTW VALUES
NEGATIVE FTW VALUES
COMPLEX
–6dB LOSS DUE TO
NCO + MIXER
–
f
S
/2 –
f
S
/3 –
f
S
/4 –
f
S
/8
f
S
/16
f
S
/8
f
S
/4
f
S
/3
f
S
/2–
f
S
/16
–
f
S
/32
f
S
/32
48-BIT NCO FTW =
ROUND ((
f
S
/3)/
f
S
× 2
48
) = +9.3825
13
(0x5555_5555_5555)
48-BIT NCO FTW =
ROUND ((
f
S
/3)/
f
S
× 2
48
) = –9.3825
13
(0xAAAA_AAAA_AAAA)
15547-081
Figure 86. DDC NCO Frequency Tuning Word Selection—Real Inputs
AD9208 Data Sheet
Rev. 0 | Page 44 of 136
NCO FREQUENCY TUNING WORD (FTW) SELECTION
48-BIT NCO FTW = MIXING FREQUENCY/ADC SAMPLE RATE × 2
48
QUADRATURE ANALOG MIXER +
2 ADCs + QUADRATURE DIGITAL
MIXER + NCO
COMPLEX INPUT—SAMPLED AT
f
S
–
f
S
/32
f
S
/32
DC
BANDWIDTH OF
INTEREST
POSITIVE FTW VALUES
IMAGE DUE TO
ANALOG I/Q
MISMATCH
REAL
I
Q
QUADRATURE MIXER
I
Q
I
–
+
Q
Q
I
Q+
+
Q
I
I
COMPLEX
I
Q
–sin(t)
ADC
SAMPLING
AT
f
S
ADC
SAMPLING
AT
f
S
90°
PHASE
48-BIT
NCO
90°
0°
48-BIT NCO FTW =
ROUND ((
f
S
/3)/
f
S
× 2
48
) = +9.3825
13
(0x5555_5555_5555)
–
f
S
/2 –
f
S
/3 –
f
S
/4 –
f
S
/8
f
S
/16
f
S
/8
f
S
/4
f
S
/3
f
S
/2–
f
S
/16
–
f
S
/32
f
S
/32
DC
15547-082
Figure 87. DDC NCO Frequency Tuning Word Selection—Complex Inputs
Data Sheet AD9208
Rev. 0 | Page 45 of 136
DDC NCO Description
Each DDC contains one NCO. Each NCO enables the
frequency translation process by creating a complex exponential
frequency (e-jωct), which can be mixed with the input spectrum
to translate the desired frequency band of interest to dc, where
it can be filtered by the subsequent low-pass filter blocks to
prevent aliasing.
When placed in variable IF mode, the NCO supports two
different additional modes.
DDC NCO Programmable Modulus Mode
This mode supports >48-bit frequency tuning accuracy for
applications that require exact rational (M/N) frequency
synthesis at a single carrier frequency. In this mode, the NCO is
set up by providing the following:
48-bit frequency tuning word (FTW)
48-bit Modulus A word (MAW)
48-bit Modulus B word (MBW)
48-bit phase offset word (POW)
DDC NCO Coherent Mode
This mode allows an infinite number of frequency hops where the
phase is referenced to a single synchronization event at time 0.
This mode is useful when phase coherency must be maintained
when switching between different frequency bands. In this mode,
the user can switch to any tuning frequency without the need to
reset the NCO. Although only one FTW is required, the NCO
contains 16 shadow registers for fast-switching applications.
Selection of the shadow registers is controlled by the CMOS
GPIO pins or through the register map of the SPI. In this mode,
the NCO can be set up by providing the following:
Up to sixteen 48-bit FTWs.
Up to sixteen 48-bit POWs.
The 48-bit MAW must be set to zero in coherent mode.
Figure 88 shows a block diagram of one NCO and its connection to
the rest of the design. The coherent phase accumulator block
contains the logic that allows an infinite number of frequency
hops. The gray lines in Figure 88 represent SPI control lines.
NCO
COS/SIN
GENERATOR
Q
cos(x)
–sin(x)
Q
I
NCO CHANNEL
SELECTION
SYSREF
DIGITAL
QUADRATURE
MIXER
FTW = FREQUENCY TUNING WORD
POW = PHASE OFFSET WORD
MAW = MODULUS A WORD (NUMERATOR)
MBW = MODULUS B WORD (DENOMINATOR)
I
COHERENT
PHASE
ACCUMULATOR
BLOCK
48-BIT
MAW/MBW
MODULUS
ERROR
NCO
CHANNEL
SELECTION
CIRCUITS
I/O
CROSSBAR
MUX
SYNCHRONIZATION
CONTROL CIRCUITS
DECIMATION
FILTERS
MAW/MBW
FTW/POW
FTW/POW
WRITE INDEX
0
1
15
0
1
15
48-BIT
FTW/POW
48-BIT
FTW/POW
48-BIT
FTW/POW
REGISTER
MAP
15547-083
Figure 88. NCO + Mixer Block Diagram
AD9208 Data Sheet
Rev. 0 | Page 46 of 136
NCO FTW/POW/MAW/MAB Description
The NCO frequency value is determined by the following settings:
48-bit twos complement number entered in the FTW
48-bit unsigned number entered in the MAW
48-bit unsigned number entered in the MBW
Frequencies between −fS/2 and +fS/2 (fS/2 excluded) are
represented using the following values:
FTW = 0x8000_0000_0000 and MAW = 0x0000_0000_0000
represents a frequency of –fS/2.
FTW = 0x0000_0000_0000 and MAW = 0x0000_0000_0000
represents dc (frequency is 0 Hz).
FTW = 0x7FFF_FFFF_FFFF and MAW = 0x0000_0000_0000
represents a frequency of +fS/2.
NCO FTW/POW/MAW/MAB Programmable Modulus
Mode
For programmable modulus mode, the MAW must be set to a
nonzero value (not equal to 0x0000_0000_0000). This mode is
only needed when frequency accuracy of >48 bits is required.
One example of a rational frequency synthesis requirement that
requires >48 bits of accuracy is a carrier frequency of 1/3 the
sample rate. When frequency accuracy of ≤48 bits is required,
coherent mode must be used (see the NCO FTW/POW/
MAW/MAB Coherent Mode section).
In programmable modulus mode, the FTW, MAW, and MBW
must satisfy the following four equations (for a detailed
description of the programmable modulus feature, see the DDS
architecture described in the AN-953 Application Note):
48
2
),mod( MBW
MAW
FTW
N
M
f
ff
s
sc
(1)
)
),mod(
2floor( 48
s
sc
f
ff
FTW (2)
MAW = mod(248 × M,N) (3)
MBW = N (4)
where:
fC is the desired carrier frequency.
fS is the ADC sampling frequency.
M is the integer representing the rational numerator of the
frequency ratio.
N is the integer representing the rational denominator of the
frequency ratio.
FTW is the 48-bit twos complement number representing the
NCO FTW.
MAW is the 48-bit unsigned number representing the NCO
MAW (must be <247).
MBW is the 48-bit unsigned number representing the NCO MBW.
mod(x) is a remainder function. For example, mod(110,100) =
10 and for negative numbers, mod(–32,10)= –2.
floor(x) is defined as the largest integer less than or equal to x.
For example, floor(3.6) = 3.
Note that Equation 1 to Equation 4 apply to the aliasing of
signals in the digital domain (that is, aliasing introduced when
digitizing analog signals).
M and N are integers reduced to their lowest terms. MAW and
MBW are integers reduced to their lowest terms. When MAW is
set to zero, the programmable modulus logic is automatically
disabled.
For example, if the ADC sampling frequency (fS) is 3000 MSPS
and the carrier frequency (fC) is 1001.5 MHz, then,
6000
2003
3000
)3000,5.1001mod(
N
M
0_FB380x5576_19F
)
3000
)3000,5.1001mod(
2floor( 48
FTW
MAW = mod(248 × 2003, 6000) = 0x0000_0000_0F80
MBW = 0x0000_0000_1770
The actual carrier frequency can be calculated based on the
following equation:
48
_2
S
ACTUALC
f
MBW
MAW
FTW
f
For the previous example, the actual carrier frequency (fC_ACTUAL)
is
MHz5.1001
2
0_17700x0000_000
0_0F800x0000_000
0_FB380x5576_19F
48
_
ACTUALC
f
A 48-bit POW is available for each NCO to create a known
phase relationship between multiple chips or individual DDC
channels inside the chip.
While in programmable modulus mode, the FTW and POW
registers can be updated at any time while still maintaining
deterministic phase results in the NCO. However, the following
procedure must be followed to update the MAW and/or MBW
registers to ensure proper operation of the NCO:
1. Write to the MAW and MBW registers for all the DDCs.
2. Synchronize the NCOs either through the DDC soft reset
bit accessible through the SPI or through the assertion of
the SYSREF± pin (see the Memory Map section).
Data Sheet AD9208
Rev. 0 | Page 47 of 136
NCO FTW/POW/MAW/MAB Coherent Mode
For coherent mode, the NCO MAW must be set to zero
(0x0000_0000_0000). In this mode, the NCO FTW can be
calculated by the following equation:
)
),mod(
2round( 48
s
sc
f
ff
FTW (5)
where:
FTW is the 48-bit twos complement number representing the
NCO FTW.
fS is the ADC sampling frequency.
fC is the desired carrier frequency.
mod(x) is a remainder function. For example mod(110,100) =
10 and for negative numbers, mod(–32,10) = –2.
round(x) is a rounding function. For example round(3.6) = 4
and for negative numbers, round(–3.4)= –3.
Note that Equation 5 applies to the aliasing of signals in the
digital domain (that is, aliasing introduced when digitizing
analog signals). The MAW must be set to zero to use coherent
mode. When MAW is zero, the programmable modulus logic is
automatically disabled.
For example, if the ADC sampling frequency (fS) is 3000 MSPS
and the carrier frequency (fC) is 416.667 MHz, then,
A_8E230x2EC6_C03
)
3000
)3000,667.416mod(
2round(
_
48
FTWNCO
The actual carrier frequency can be calculated based on the
following equation:
48
_2
S
ACTUALC
fFTW
f
For the previous example, the actual carrier frequency (fC_ACTUAL) is
fC_ACTUAL = 48
2
3000667.416
= 416.66699 MHz
A 48-bit POW is available for each NCO to create a known
phase relationship between multiple chips or individual DDC
channels inside the chip.
While in coherent mode, the FTW and POW registers can be
updated at any time while still maintaining deterministic phase
results in the NCO.
NCO Channel Selection
When configured in coherent mode, only one FTW is required
in the NCO. In this mode, the user can switch to any tuning
frequency without the need to reset the NCO by writing to the
FTW directly. However, for fast-switching applications, where
either all FTWs are known beforehand or it is possible to queue
up the next set of FTWs, the NCO contains 16 additional
shadow registers (see Figure 88). These shadow registers are
hereafter referred to as the NCO channels.
Figure 89 shows a simplified block diagram of the NCO channel
selection block. The gray lines in Figure 89 represent SPI
control lines.
NCO CHANNEL
SELECTION
NCO CHANNEL SELECTION
COUNTER
GPIO
CMOS
PINS
GPIO
SELECTION
MUX
INC
[0] NCO
REGISTER MAP NCO
CHANNEL SELECTION
0x0314, 0x0334, 0x0354, 0x0374
NCO CHANNEL MODE
[3:0]
IN
IN
IN
IN
REGISTER
MAP
15547-084
Figure 89. NCO Channel Selection Block
AD9208 Data Sheet
Rev. 0 | Page 48 of 136
Only one NCO channel is active at a time and NCO channel
selection is controlled either by the CMOS GPIO pins or
through the register map.
Each NCO channel selector supports three different modes,
described as follows:
GPIO level control mode. In this mode, the GPIO pins
determine the exact NCO channel selected.
GPIO edge control mode. A low to high transition on a
single GPIO pin determines the exact NCO channel
selected. The internal channel selection counter is reset by
either SYSREF± or by the DDC soft reset.
Register map mode. In this mode, the NCO channel
selected is determined directly through the register map.
The following procedure must be followed to use GPIO level
control mode for NCO channel selection:
1. Configure one or more GPIO pins as NCO channel
selection inputs. The GPIO pins not configured as NCO
channel selection inputs are internally tied low.
a. To use GPIO_A0, write Bits[2:0] in Register 0x0040 to
0x6 and Bits[3:0] in Register 0x0041 to 0x0.
b. To use GPIO_B0, write Bits[5:3] in Register 0x0040 to
0x6 and Bits[7:4] in Register 0x0041 to 0x0.
c. To use GPIO_A1, write Bits[3:0] in Register 0x0042 to
0x0.
d. To use GPIO_B1, write Bits[7:4] in Register 0x0042 to
0x0.
2. Configure the NCO channel selector in GPIO level control
mode by setting Bits[7:4] in the NCO control registers
(Register 0x0314, Register 0x0334, Register 0x0354, and
Register 0x0374) to 0x1 through 0x6, depending on the
desired GPIO pin order.
3. Select the desired NCO channel through the GPIO pins.
The following procedure must be followed to use GPIO edge
control mode for NCO channel selection:
1. Configure one or more GPIO pins as NCO channel
selection inputs.
a. To use GPIO_A0, write Bits[2:0] in Register 0x0040 to
0x6 and Bits[3:0] in Register 0x0041 to 0x0.
b. To use GPIO_B0, write Bits[5:3] in Register 0x0040 to
0x6 and Bits[7:4] in Register 0x0041 to 0x0.
c. To use GPIO_A1, write Bits[3:0] in Register 0x0042 to
0x0.
d. To use GPIO_B1, write Bits[7:4] in Register 0x0042 to
0x0.
2. Configure the NCO channel selector in GPIO edge control
mode by setting Bits[7:4] in the NCO control registers
(Register 0x0314, Register 0x0334, Register 0x0354, and
Register 0x0374) to 0x8 through 0xB, depending on the
desired GPIO pin.
3. Configure the wrap point for the NCO channel selection
by setting Bits[3:0] in the NCO control registers
(Register 0x0314, Register 0x0334, Register 0x0354, and
Register 0x0374). A value of 4 causes the channel selection
to wrap at Channel 4 (for example, 0, 1, 2, 3, 4, 0, 1, 2, 3, 4).
4. Transition the selected GPIO pin from low to high to
increment the NCO channel selection.
Figure 90 shows an example use case for coherent mode using
three NCO channels. In this example, NCO Channel 0 is actively
downconverting Bandwidth 0 (B0), while NCO Channel 1 and
Channel 2 are in standby mode and are tuned to Bandwidth 1
and Bandwidth 2 (B1 and B2), respectively.
f
S
/2
DC
B1
NCO CHANNEL 0
CARRIER FREQUENCY 0
(ACTIVE)
NCO CHANNEL 1
CARRIER FREQUENCY 1
(STANDBY)
NCO CHANNEL 2
CARRIER FREQUENCY 2
(STANDBY)
B2
B0
f
0
f
1
f
2
ACTIVE
DDC
15547-085
Figure 90. NCO Coherent Mode with Three NCO Channels (B0 Selected)
Data Sheet AD9208
Rev. 0 | Page 49 of 136
The phase coherent NCO switching feature allows an infinite
number of frequency hops that are all phase coherent. The
initial phase of the NCO is established at time, t0, from
SYSREF± synchronization. Switching the NCO FTW does not
affect the phase. With this feature, only one FTW is required,
but the user may wish to use all 16 channels to queue up the
next hop.
After SYSREF± synchronization at startup, all NCOs across
multiple chips are inherently synchronized.
Setting Up the Multichannel NCO Feature
The first step to configure the multichannel NCO is to program
the FTWs. The AD9208 memory map has an FTW index
register for each DDC. This index determines which NCO
channel receives the FTW from the register map. The following
sequence describes the method for programming the FTWs:
1. Write the FTW index register with the desired DDC channel.
2. Write the FTW with the desired value. This value is applied
to the NCO channel index mentioned in Step 1.
3. Repeat Step 1 and Step 2 for other NCO channels.
After setting the FTWs, the user must then select an active
NCO channel. This selection can be performed either through
the SPI registers or through the external GPIO pins. The following
sequence describes the method for selecting the active NCO
channel using the SPI:
1. Set the NCO channel select mode bits (Bits[7:4] in
Register 0x0314, Register 0x0334, Register 0x0354, and
Register 0x0374) to 0x0 to enable SPI selection.
2. Choose the active NCO channel using Bits[3:0] in
Register 0x0314, Register 0x0334, Register 0x0354,
and Register 0x0374.
The following sequence describes the method for selecting the
active NCO channel using the GPIO CMOS pins:
1. Set the NCO channel select mode bits (Bits[7:4] in
Register 0x0314, Register 0x0334, Register 0x0354, and
Register 0x0374) to a nonzero value to enable GPIO pin
selection.
2. Configure the GPIO pins as NCO channel selection inputs
by writing to Register 0x0040, Register 0x0041, and
Register 0x0042.
3. NCO switching is performed by externally controlling the
GPIO CMOS pins.
NCO Synchronization
Each NCO contains a separate phase accumulator word (PAW).
The initial reset value of each PAW is set to zero and incremented
every clock cycle. The instantaneous phase of the NCO is
c a l c u l a t e d u s i n g t h e PAW, F T W, M AW, M B W, a n d P O W. D u e t o
this architecture, the FTW and POW registers can be updated at
any time while still maintaining deterministic phase results in
the PAW of the NCO.
Two methods can be used to synchronize multiple PAWs within
the chip:
Using the SPI. Use the DDC soft reset bit in the DDC
synchronization control register (Register 0x0300, Bit 4) to
reset all the PAWs in the chip. This reset is accomplished
by setting the DDC soft reset bit high, and then setting this
bit low. Note that this method can only be used to
synchronize DDC channels within the same chip.
Using the SYSREF± pin. When the SYSREF± pin is enabled
in the SYSREF control registers (Register 0x0120 and
Register 0x0121), and the DDC synchronization is enabled
in the DDC synchronization control register (Register 0x0300,
Bits[1:0]), any subsequent SYSREF± event resets all the
PAWs in the chip. Note that this method can be used to
synchronize DDC channels within the same chip or DDC
channels within separate chips.
NCO Multichip Synchronization
In some applications, it is necessary to synchronize all the
NCOs and local multiframe clocks (LMFCs) within multiple
devices in a system. For applications requiring multiple NCO
tuning frequencies in the system, a designer likely needs to
generate a single SYSREF pulse at all devices simultaneously. For
many systems, generating
or receiving a single-shot SYSREF pulse at all devices is
challenging because of the following factors:
Enabling or disabling the SYSREF pulse is often an
asynchronous event.
Not all clock generation chips support this feature.
For these reasons, the AD9208 contains a synchronization
triggering mechanism that allows the following:
Multichip synchronization of all NCOs and LMFCs at
system startup.
Multichip synchronization of all NCOs after applying new
tuning frequencies during normal operation.
The synchronization triggering mechanism uses a master/slave
arrangement, as shown in Figure 91.
AD9208 Data Sheet
Rev. 0 | Page 50 of 136
CLOCK
GENERATION
SYSREF±
DEVICE_CLOCK±
MNTO
SNTI
SNTI
SNTI
1 LINK,
L LANES
1 LINK,
L LANES
1 LINK,
L LANES
1 LINK,
L LANES
ADC DEVICE 0
(MASTER)
ADC DEVICE 1
(SLAVE)
ADC DEVICE 2
(SLAVE)
ADC DEVICE 3
(SLAVE)
MNTO = MASTER NEXT TRIGGER OUTPUT (CMOS)
SNTI = SLAVE NEXT TRIGGER INPUT (CMOS)
15547-086
Figure 91. System Using Master/Slave Synchronization Triggering
Each device has an internal next synchronization trigger enable
(NSTE) signal that controls whether the next SYSREF signal
causes a synchronization event. Slave ADC devices must source
their NSTE from an external slave next trigger input (SNTI) pin.
Master devices can either use an external master next trigger
output (MNTO) pin (default setting), or use an external SNTI
pin.
See Table 46 (Register 0x0041 and Register 0x0042) to configure
the FD/GPIO pins for this operation.
NCO Multichip Synchronization at Startup
Figure 92 shows a timing diagram along with the required
sequence of events for NCO multichip synchronization using
triggering and SYSREF at startup. Using this startup sequence
synchronizes all the NCOs and LMFCs in the system at once.
NCO Multichip Synchronization During Normal Operation
See the Setting Up the Multichannel NCO Feature section.
MNTO
SNTI
SYSREF
DEVICE
CLOCK
LMFCs DON’T CARE
DON’T CARE
NCOs
NCO
SYNCHRONIZED
LMFC
SYNCHRONIZED
BOARD PROPAGATION
DELAY
NSTE
INPUT DELAY
CONFIGURE MASTER
AND SLAVE DEVICES ENABLE TRIGGER IN
MASTER DEVICES
MNTO SET HIGH
SNTI SET HIGH
SYSTEM
SYNCHRONIZATION
ACHIEVED
SYSREF
IGNORED
MNTO = MASTER NEXT TRIGGER OUTPUT (CMOS)
SNTI = SLAVE NEXT TRIGGER INPUT (CMOS)
NSTE = NEXT SYNCHRONIZATION TRIGGER ENABLE
LMFC = LOCAL MULTIFRAME CLOCK
NCO = NUMERICALLY CONTROLLED OSCILLATOR
15547-087
Figure 92. NCO Multichip Synchronization at Startup (Using Triggering and SYSREF)
Data Sheet AD9208
Rev. 0 | Page 51 of 136
DDC Mixer Description
When not bypassed (Register 0x0200 ≠ 0x00), the digital
quadrature mixer performs a similar operation to an analog
quadrature mixer. It performs the downconversion of input
signals (real or complex) by using the NCO frequency as a local
oscillator. For real input signals, a real mixer operation (with
two multipliers) is performed. For complex input signals, a
complex mixer operation (with four multipliers and two adders)
is performed. The selection of real or complex inputs can be
controlled individually for each DDC block using Bit 7 of the
DDC control registers (Register 0x0310, Register 0x0330,
Register 0x0350, and Register 0x0370).
DDC NCO + Mixer Loss and SFDR
When mixing a real input signal down to baseband, −6 dB of
loss is introduced in the signal due to filtering of the negative
image. An additional −0.05 dB of loss is introduced by the NCO.
The total loss of a real input signal mixed down to baseband is
−6.05 dB. For this reason, it is recommended that the user
compensate for this loss by enabling the 6 dB of gain in the gain
stage of the DDC to recenter the dynamic range of the signal
within the full scale of the output bits (see the DDC Gain Stage
(Optional) section).
When mixing a complex input signal (where I and Q DDC
inputs come from the different ADCs) down to baseband, the
maximum value each I/Q sample is able to reach is 1.414 × full
scale, after the sample passes through the complex mixer. To
avoid overrange of the I/Q samples and to keep the data bit
widths aligned with real mixing, −3.06 dB of loss is introduced
in the mixer for complex signals. An additional −0.05 dB of loss
is introduced by the NCO. The total loss of a complex input
signal mixed down to baseband is −3.11 dB.
The worst case spurious signal from the NCO is greater than
102 dBc SFDR for all output frequencies.
DDC DECIMATION FILTERS
After the frequency translation stage, there are multiple
decimation filter stages that reduce the output data rate. After
the carrier of interest is tuned down to dc (carrier frequency =
0 Hz), these filters efficiently lower the sample rate, while
providing sufficient alias rejection from unwanted adjacent
carriers around the bandwidth of interest.
Figure 93 shows a simplified block diagram of the decimation
filter stage, and Table 16 describes the filter characteristics of
the different finite impulse response (FIR) filter blocks.
Table 17 and Table 18 show the different filter configurations
selectable by including different filters. In all cases, the DDC
filtering stage provides 80% of the available output bandwidth,
<±0.005 dB of passband ripple and >100 dB of stop band alias
rejection.
DECIMATION FILTERS DCM = 3
FIR = FINITE IMPULSE RESPONSE FILTER
DCM = DECIMATION
HB1
FIR
TB1
FIR
DCM = 2
HB4
FIR
TB2
FIR
DCM = 3
DCM = 3
DCM = 2
HB4
FIR
DCM = 2
FB2
FIR
DCM = 5
FB2
FIR
DCM = 5
DCM = 2
TB1
FIR
HB1
FIR
DCM = 3
I
TB2
FIR
Q
I
Q
HB3
FIR
DCM = 2
HB2
FIR
DCM = 2
HB3
FIR
DCM = 2
HB2
FIR
DCM = 2
Q
I
Q
I
Q
I
I
Q
I
Q
I
Q
I
I
Q
Q
NCO
AND
MIXERS
(OPTIONAL)
NOTES
1. TB1 IS ONLY SUPPORTED IN DDC0 AND DDC1
GAIN = 0dB OR +6dB
COMPLEX TO REAL CONVERSION
(OPTIONAL)
15547-088
Figure 93. DDC Decimation Filter Block Diagram
AD9208 Data Sheet
Rev. 0 | Page 52 of 136
Table 16. DDC Decimation Filter Characteristics
Filter Name Filter Type
Decimation
Ratio
Pass Band
(rad/sec)
Stop Band
(rad/sec)
Pass-Band
Ripple (dB)
Stop-Band
Attenuation (dB)
HB4 FIR low-pass 2 0.1 x π/2 1.9 x π/2 <±0.001 >100
HB3 FIR low-pass 2 0.2 x π/2 1.8 x π/2 <±0.001 >100
HB2 FIR low-pass 2 0.4 x π/2 1.6 x π/2 <±0.001 >100
HB1 FIR low-pass 2 0.8 x π/2 1.2 x π/2 <±0.001 >100
TB2 FIR low-pass 3 0.4 x π/3 1.6 x π/3 <±0.002 >100
TB11 FIR low-pass 3 0.8 x π/3 1.2 x π/3 <±0.005 >100
FB2 FIR low-pass 5 0.4 x π/5 1.6 x π/5 <±0.001 >100
1 TB1 is only supported in DDC0 and DDC1.
Table 17. DDC Filter Configurations1
ADC
Sample
Rate DDC Filter Configuration
Real (I) Output Complex (I/Q) Outputs Alias
Protected
Bandwidth
Ideal2 SNR
Improvement
(dB)
Decimation
Ratio
Sample
Rate
Decimation
Ratio Sample Rate
fS HB1 1 fS 2 fS/2 (I) + fS/2 (Q) fS/2 × 80% 1
TB13 N/A N/A 3 fS/3 (I) + fS/3 (Q) fS/3 × 80% 2.7
HB2 + HB1 2 fS/2 4 fS/4 (I) + fS/4 (Q) fS/4 × 80% 4
TB2 + HB1 3 fS/3 6 fS/6 (I) + fS/6 (Q) fS/6 × 80% 5.7
HB3 + HB2 + HB1 4 fS/4 8 fS/8 (I) + fS/8 (Q) fS/8 × 80% 7
FB2 + HB1 5 fS/5 10 fS/10 (I) + fS/10 (Q) fS/10 × 80% 8
TB2 + HB2 + HB1 6 fS/6 12 fS/12 (I) + fS/12 (Q) fS/12 × 80% 8.8
FB2 + TB13 N/A N/A 15 fS/15 (I) + fS/15 (Q) fS/15 × 80% 9.7
HB4 + HB3 + HB2 + HB1 8 fS/8 16 fS/16 (I) + fS/16 (Q) fS/16 × 80% 10
FB2 + HB2 + HB1 10 fS/10 20 fS/20 (I) + fS/20 (Q) fS/20 × 80% 11
TB2 + HB3 + HB2 + HB1 12 fS/12 24 fS/24 (I) + fS/24 (Q) fS/24 × 80% 11.8
HB2 + FB2 + TB13 N/A N/A 30 fS/30 (I) + fS/30 (Q) fS/30 × 80% 12.7
FB2 + HB3 + HB2 + HB1 20 fS/20 40 fS/40 (I) + fS/40 (Q) fS/40 × 80% 14
TB2 + HB4 + HB3 + HB2 + HB1 24 fS/24 48 fS/48 (I) + fS/48 (Q) fS/48 × 80% 14.8
1 N/A means not applicable.
2 Ideal SNR improvement due to oversampling + filtering = 10log(bandwidth/fS/2).
3 TB1 is only supported in in DDC0 and DDC1.
Table 18. DDC Filter Configurations (fS = 3000 MSPS)1
ADC
Sample
Rate
(MSPS) DDC Filter Configuration
Real (I) Output Complex (I/Q) Outputs Alias
Protected
Bandwidth
(MHz) Decimation Ratio
Sample
Rate
(MSPS)
Decimation
Ratio Sample Rate (MSPS)
3000 HB1 1 3000 2 1500 (I) + 1500 (Q) 1200
TB12 N/A N/A 3 1000 (I) + 1000 (Q) 800
HB2 + HB1 2 1500 4 750 (I) + 750 (Q) 600
TB2 + HB1 3 1000 6 500 (I) + 500 (Q) 400
HB3 + HB2 + HB1 4 750 8 375 (I) + 375 (Q) 300
FB2 + HB1 5 600 10 300 (I) + 300 (Q) 240
TB2 + HB2 + HB1 6 500 12 250 (I) + 250 (Q) 200
FB2 + TB12 N/A N/A 15 200 (I) + 200 (Q) 160
HB4 + HB3 + HB2 + HB1 8 375 16 187.5 (I) + 187.5 (Q) 150
FB2 + HB2 + HB1 10 300 20 150 (I) + 150 (Q) 120
TB2 + HB3 + HB2 + HB1 12 250 24 125 (I) + 125 (Q) 100
HB2 + FB2 + TB12 N/A N/A 30 100 (I) + 100 (Q) 80
FB2 + HB3 + HB2 + HB1 20 150 40 75 (I) + 75 (Q) 60
TB2 + HB4 + HB3 + HB2 + HB1 24 125 48 62.5 (I) + 62.5 (Q) 50
1 N/A means not applicable.
2 TB1 is only supported in in DDC0 and DDC1.
Data Sheet AD9208
Rev. 0 | Page 53 of 136
HB4 Filter Description
The first decimate by 2, half-band, low-pass, FIR filter (HB4) uses
an 11-tap, symmetrical, fixed coefficient filter implementation
that is optimized for low power consumption. The HB4 filter is
only used when complex outputs (decimate by 16) or real outputs
(decimate by 8) are enabled; otherwise, it is bypassed. Table 19
and Figure 94 show the coefficients and response of the HB4 filter.
Table 19. HB4 Filter Coefficients
HB4 Coefficient
Number
Normalized
Coefficient
Decimal
Coefficient (15-Bit)
C1, C11 0.006042 99
C2, C10 0 0
C3, C9 −0.049377 −809
C4, C8 0 0
C5, C7 0.293304 4806
C6 0.5 8192
–160
–140
–120
–100
–80
–60
–40
–20
0
20
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
MAGNITUDE (dB)
NORMALIZED FREQUENCY (× RAD/s)
15547-089
Figure 94. HB4 Filter Response
HB3 Filter Description
The second decimate by 2, half-band, low-pass, FIR filter (HB3)
uses an 11-tap, symmetrical, fixed coefficient filter implementa-
tion that is optimized for low power consumption. The HB3
filter is only used when complex outputs (decimate by 8 or 16)
or real outputs (decimate by 4 or 8) are enabled; otherwise, it is
bypassed. Table 20 and Figure 95 show the coefficients and
response of the HB3 filter.
Table 20. HB3 Filter Coefficients
HB3 Coefficient
Number
Normalized
Coefficient
Decimal Coefficient
(17-Bit)
C1, C11 0.006637 435
C2, C10 0 0
C3, C9 −0.051055 −3346
C4, C8 0 0
C5, C7 0.294418 19295
C6 0.500000 65,536
–160
–140
–120
–100
–80
–60
–40
–20
0
20
00.10.2
0.3 0.40.50.60.70.80.91.0
MAGNITUDE (dB)
NORMALIZED FREQUENCY (× RAD/s)
15547-090
Figure 95. HB3 Filter Response
HB2 Filter Description
The third decimate by 2, half-band, low-pass, FIR filter (HB2)
uses a 19-tap, symmetrical, fixed coefficient filter implementa-
tion that is optimized for low power consumption.
The HB2 filter is only used when complex or real outputs
(decimate by 4, 8, or 16) is enabled; otherwise, it is bypassed.
Table 21 and Figure 96 show the coefficients and response of
the HB2 filter.
Table 21. HB2 Filter Coefficients
HB2 Coefficient
Number
Normalized
Coefficient
Decimal Coefficient
(18-Bit)
C1, C19 0.000671 88
C2, C18 0 0
C3, C17 −0.005325 −698
C4, C16 0 0
C5, C15 0.022743 2981
C6, C14 0 0
C7, C13 −0.074180 −9723
C8, C12 0 0
C9, C11 0.306091 40120
C10 0.5 65536
–160
–140
–120
–100
–80
–60
–40
–20
0
20
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
MAGNITUDE (dB)
NORMALIZED FREQUENCY (× RAD/s)
15547-091
Figure 96. HB2 Filter Response
AD9208 Data Sheet
Rev. 0 | Page 54 of 136
HB1 Filter Description
The fourth and final decimate by 2, half-band, low-pass, FIR
filter (HB1) uses a 63-tap, symmetrical, fixed coefficient filter
implementation that is optimized for low power consumption.
The HB1 filter is always enabled and cannot be bypassed.
Table 22 and Figure 97 show the coefficients and response of
the HB1 filter.
Table 22. HB1 Filter Coefficients
HB1 Coefficient
Number
Normalized
Coefficient
Decimal Coefficient
(20-Bit)
C1, C63 −0.000019 −10
C2, C62 0 0
C3, C61 0.000072 38
C4, C60 0 0
C5, C59 −0.000195 −102
C6, C58 0 0
C7, C57 0.000443 232
C8, C56 0 0
C9, C55 −0.000891 −467
C10, C54 0 0
C11, C53 0.001644 862
C12, C52 0 0
C13, C51 −0.00284 −1489
C14, C50 0 0
C15, C49 0.004654 2440
C16, C48 0 0
C17, C47 −0.007311 −3833
C18, C46 0 0
C19, C45 0.011122 5831
C20, C44 0 0
C21, C43 −0.016554 −8679
C22, C42 0 0
C23, C41 0.02442 12803
C24, C40 0 0
C25, C39 −0.036404 −19086
C26, C38 0 0
C27, C37 0.056866 29814
C28, C36 0 0
C29, C35 −0.101892 −53421
C30, C34 0 0
C31, C33 0.316883 166138
C32 0.5 262144
–160
–140
–120
–100
–80
–60
–40
–20
0
20
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
MAGNITUDE (dB)
NORMALIZED FREQUENCY (× RAD/s)
15547-092
Figure 97. HB1 Filter Response
TB2 Filter Description
The TB2 uses a 26-tap, symmetrical, fixed coefficient filter
implementation that is optimized for low power consumption.
The TB2 filter is only used when decimation ratios of 6, 12, or
24 are required. Table 19 and Figure 94 show the coefficients
and response of the TB2 filter.
Table 23. TB2 Filter Coefficients
TB2 Coefficient
Number
Normalized
Coefficient
Decimal Coefficient
(19-Bit)
C1, C26 −0.000190 −50
C2, C25 −0.000793 208
C3, C24 −0.00113 −298
C4, C23 0.000915 240
C5, C22 0.006290 1649
C6, C21 0.009822 2575
C7, C20 0.000915 240
C8, C19 −0.023483 −6156
C9, C18 −0.043151 −11312
C10, C17 −0.019317 −5064
C11, C16 0.071327 18698
C12, C15 0.201171 52736
C13, C14 0.297756 78055
–160
–140
–120
–100
–80
–60
–40
–20
0
20
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
MAGNITUDE (dB)
NORMALIZED FREQUENCY (× RAD/s)
15547-093
Figure 98. TB2 Filter Response
Data Sheet AD9208
Rev. 0 | Page 55 of 136
TB1 Filter Description
The TB1 decimate by 3, low-pass, FIR filter uses a 76-tap,
symmetrical, fixed coefficient filter implementation. Table 24
shows the TB1 filter coefficients, and Figure 99 shows the TB1
filter response. TB1 is only supported in DDC0 and DDC1.
Table 24. TB1 Filter Coefficients
TB1 Coefficient
Number
Decimal
Coefficient
Quantized Coefficient
(22-Bit)
1, 96 −0.000023 −96
2, 75 −0.000053 −224
3, 74 −0.000037 −156
4, 73 0.000090 379
5, 72 0.000291 1220
6, 71 0.000366 1534
7, 70 0.000095 398
8, 69 −0.000463 −1940
9, 68 −0.000822 −3448
10, 67 −0.000412 −1729
11, 66 0.000739 3100
12, 65 0.001665 6984
13, 64 0.001132 4748
14, 63 −0.000981 −4114
15, 62 −0.002961 −12418
16, 61 −0.002438 −10226
17, 60 0.001087 4560
18, 59 0.004833 20272
19, 58 0.004614 19352
20, 57 −0.000871 −3652
21, 56 −0.007410 −31080
22, 55 −0.008039 −33718
23, 54 0.000053 222
24, 53 0.010874 45608
25, 52 0.013313 55840
26, 51 0.001817 7620
27, 50 −0.015579 −65344
28, 49 −0.021590 −90556
29, 48 −0.005603 −23502
30, 47 0.022451 94167
31, 46 0.035774 150046
32, 45 0.013541 56796
33, 44 −0.034655 −145352
34, 43 −0.066549 −279128
35, 42 −0.035213 −147694
36, 41 0.071220 298720
37, 40 0.210777 884064
38, 39 0.309200 1296880
MAGNITUDE (dB)
NORMALIZED FREQUENCY (× RAD/s)
–160
–140
–120
–100
–80
–60
–40
–20
0
20
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
15547-094
Figure 99. TB1 Filter Response
AD9208 Data Sheet
Rev. 0 | Page 56 of 136
FB2 Filter Description
The FB2 decimate by 5, low-pass, FIR filter uses a 48-tap,
symmetrical, fixed coefficient filter implementation. Table 24
shows the FB2 filter coefficients, and Figure 100 shows the FB2
filter response.
Table 25. FB2 Filter Coefficients
FB2 Coefficient
Number
Decimal
Coefficient
Quantized Coefficient
(21-Bit)
1, 48 0.000007 7
2, 47 −0.000004 −4
3, 46 −0.000069 −72
4, 45 −0.000244 −256
5, 44 −0.000544 −570
6, 43 −0.000870 −912
7, 42 −0.000962 −1009
8, 41 −0.000448 −470
9, 40 0.000977 1024
10, 39 0.003237 3394
11, 38 0.005614 5887
12, 37 0.006714 7040
13, 36 0.004871 5108
14, 35 −0.001011 −1060
15, 34 −0.010456 −10964
16, 33 −0.020729 −21736
17, 32 −0.026978 −28288
18, 31 −0.023453 −24592
19, 30 −0.005608 −5880
20, 29 0.027681 29026
21, 28 0.072720 76252
22, 27 0.121223 127112
23, 26 0.162346 170232
24, 25 0.185959 194992
–160
–140
–120
–100
–80
–60
–40
–20
0
20
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
MAGNITUDE (dB)
NORMALIZED FREQUENCY (× RAD/s)
15547-095
Figure 100. FB2 Filter Response
Data Sheet AD9208
Rev. 0 | Page 57 of 136
DDC GAIN STAGE
Each DDC contains an independently controlled gain stage.
The gain is selectable as either 0 dB or 6 dB. When mixing a real
input signal down to baseband, it is recommended that the user
enable the 6 dB of gain to recenter the dynamic range of the
signal within the full scale of the output bits.
When mixing a complex input signal down to baseband, the
mixer has already recentered the dynamic range of the signal
within the full scale of the output bits, and no additional gain is
necessary. However, the optional 6 dB gain compensates for low
signal strengths. The downsample by 2 portion of the HB1 FIR
filter is bypassed when using the complex to real conversion
stage. The TB1 filter does not have the 6 dB gain stage.
DDC COMPLEX TO REAL CONVERSION
Each DDC contains an independently controlled complex to
real conversion block. The complex to real conversion block
reuses the last filter (HB1 FIR) in the filtering stage along with
an fS/4 complex mixer to upconvert the signal. After upconverting
the signal, the Q portion of the complex mixer is no longer
needed and is dropped. The TB1 filter does not support
complex to real conversion.
Figure 101 shows a simplified block diagram of the complex to
real conversion.
LOW-PASS
FILTER
2
I
Q
REAL
HB1 FIR
LOW-PASS
FILTER
2
HB1 FIR
0
1
COMPLEX TO
REAL ENABLE
Q
90°
0°
+
–
COMPLEX TO REAL CONVERSION
I
Q
I
Q
GAIN STAGE
cos(wt)
sin(wt)
I/REAL
0dB
OR
6dB
0dB
OR
6dB
0dB
OR
6dB
0dB
OR
6dB
f
S
/4
15547-096
Figure 101. Complex to Real Conversion Block
AD9208 Data Sheet
Rev. 0 | Page 58 of 136
DDC MIXED DECIMATION SETTINGS
The AD9208 also supports DDCs with different decimation
rates. In this scenario, the chip decimation ratio must be set to
the lowest decimation ratio of all the DDC channels. Samples of
higher decimation ratio DDCs are repeated to match the chip
decimation ratio sample rate. Only mixed decimation ratios that
are integer multiples of 2 are supported. For example, decimate
by 1, 2, 4, 8, or 16 can be mixed together; decimate by 3, 6, 12,
24, or 48 can be mixed together; or decimate by 5, 10, 20, or 40
can be mixed together.
Table 26 shows the DDC sample mapping when the chip
decimation ratio is different than the DDC decimation ratio.
For example, if the chip decimation ratio is set to decimate by 4,
DDC0 is set to use the HB2 + HB1 filters (complex outputs are
decimate by 4) and DDC1 is set to use the HB4 + HB3 + HB2 +
HB1 filters (real outputs are decimate by 8), then DDC1 repeats
its output data two times for every one DDC0 output. The
resulting output samples are shown in Table 27.
Table 26. Sample Mapping when the Chip Decimation Ratio (DCM) Does Not Match DDC DCM
Sample Index DDC DCM = Chip DCM DDC DCM = 2 × Chip DCM DDC DCM = 4 × Chip DCM DDC DCM = 8 × Chip DCM
0 N N N N
1 N + 1 N N N
2 N + 2 N + 1 N N
3 N + 3 N + 1 N N
4 N + 4 N + 2 N + 1 N
5 N + 5 N + 2 N + 1 N
6 N + 6 N + 3 N + 1 N
7 N + 7 N + 3 N + 1 N
8 N + 8 N + 4 N + 2 N + 1
9 N + 9 N + 4 N + 2 N + 1
10 N + 10 N + 5 N + 2 N + 1
11 N + 11 N + 5 N + 2 N + 1
12 N + 12 N + 6 N + 3 N + 1
13 N + 13 N + 6 N + 3 N + 1
14 N + 14 N + 7 N + 3 N + 1
15 N + 15 N + 7 N + 3 N + 1
16 N + 16 N + 8 N + 4 N + 2
17 N + 17 N + 8 N + 4 N + 2
18 N + 18 N + 9 N + 4 N + 2
19 N + 19 N + 9 N + 4 N + 2
20 N + 20 N + 10 N + 5 N + 2
21 N + 21 N + 10 N + 5 N + 2
22 N + 22 N + 11 N + 5 N + 2
23 N + 23 N + 11 N + 5 N + 2
24 N + 24 N + 12 N + 6 N + 3
25 N + 25 N + 12 N + 6 N + 3
26 N + 26 N + 13 N + 6 N + 3
27 N + 27 N + 13 N + 6 N + 3
28 N + 28 N + 14 N + 7 N + 3
29 N + 29 N + 14 N + 7 N + 3
30 N + 30 N + 15 N + 7 N + 3
31 N + 31 N + 15 N + 7 N + 3
Data Sheet AD9208
Rev. 0 | Page 59 of 136
Table 27. Chip DCM = 4, DDC0 DCM = 4 (Complex), and DDC1 DCM = 8 (Real)1
DDC Input Samples
DDC0 DDC1
Output Port I Output Port Q Output Port I Output Port Q
N I0[N] Q0[N] I1[N] Not applicable
N + 1 I0[N] Q0[N] I1[N] Not applicable
N + 2 I0[N] Q0[N] I1[N] Not applicable
N + 3 I0[N] Q0[N] I1[N] Not applicable
N + 4 I0[N + 1] Q0[N + 1] I1[N] Not applicable
N + 5 I0[N + 1] Q0[N + 1] I1[N] Not applicable
N + 6 I0[N + 1] Q0[N + 1] I1[N] Not applicable
N + 7 I0[N + 1] Q0[N + 1] I1[N] Not applicable
N + 8 I0[N + 2] Q0[N + 2] I1[N + 1] Not applicable
N + 9 I0[N + 2] Q0[N + 2] I1[N + 1] Not applicable
N + 10 I0[N + 2] Q0[N + 2] I1[N + 1] Not applicable
N + 11 I0[N + 2] Q0[N + 2] I1[N + 1] Not applicable
N + 12 I0[N + 3] Q0[N + 3] I1[N + 1] Not applicable
N + 13 I0[N + 3] Q0[N + 3] I1[N + 1] Not applicable
N + 14 I0[N + 3] Q0[N + 3] I1[N + 1] Not applicable
N + 15 I0[N + 3] Q0[N + 3] I1[N + 1] Not applicable
1 DCM means decimation.
DDC EXAMPLE CONFIGURATIONS
Table 28 describes the register settings for multiple DDC example configurations.
Table 28. DDC Example Configurations (Per ADC Channel Pair)
Chip
Application
Layer
Chip
Decimation
Ratio
DDC
Input
Type
DDC
Output
Type
Bandwidth
Per DDC1
No. of Virtual
Converters
Required Register Settings
One DDC 2 Complex Complex 40% × fS 2 0x0200 = 0x01 (one DDC; I/Q selected)
0x0201 = 0x01 (chip decimate by 2)
0x0310 = 0x83 (complex mixer; 0 dB gain; variable IF;
complex outputs; HB1 filter)
0x0311 = 0x04 (DDC I Input = ADC Channel A; DDC Q
input = ADC Channel B)
0x0316, 0x0317, 0x0318, 0x0319, 0x031A, 0x031B,
0x031D, 0x031E, 0x031F, 0x0320, 0x0321, 0x0322 = FTW
and POW set as required by application for DDC0
Two DDCs 4 Complex Complex 20% × fS 4 0x0200 = 0x02 (two DDCs; I/Q selected)
0x0201 = 0x02 (chip decimate by 4)
0x0310, 0x0330 = 0x80 (complex mixer; 0 dB gain;
variable IF; complex outputs; HB2+HB1 filters)
0x0311, 0x0331 = 0x04 (DDC I input = ADC Channel A;
DDC Q input = ADC Channel B)
0x0316, 0x0317, 0x0318, 0x0319, 0x031A, 0x031B,
0x031D, 0x031E, 0x031F, 0x0320, 0x0321, 0x0322 = FTW
and POW set as required by application for DDC0
0x0336, 0x0337, 0x0338, 0x0339, 0x033A, 0x033B,
0x033D, 0x033E, 0x033F, 0x0340, 0x0341, 0x0342 = FTW
and POW set as required by application for DDC1
AD9208 Data Sheet
Rev. 0 | Page 60 of 136
Chip
Application
Layer
Chip
Decimation
Ratio
DDC
Input
Type
DDC
Output
Type
Bandwidth
Per DDC1
No. of Virtual
Converters
Required Register Settings
Two DDCs 4 Complex Real 10% × fS 2 0x0200 = 0x22 (two DDCs; I only selected)
0x0201 = 0x02 (chip decimate by 4)
0x0310, 0x0330 = 0x89 (complex mixer; 0 dB gain;
variable IF; real output; HB3 + HB2 + HB1 filters)
0x0311, 0x0331 = 0x04 (DDC I Input = ADC Channel A;
DDC Q input = ADC Channel B)
0x0316, 0x0317, 0x0318, 0x0319, 0x031A, 0x031B,
0x031D, 0x031E, 0x031F, 0x0320, 0x0321, 0x0322 = FTW
and POW set as required by application for DDC0
0x0336, 0x0337, 0x0338, 0x0339, 0x033A, 0x033B,
0x033D, 0x033E, 0x033F, 0x0340, 0x0341, 0x0342 = FTW
and POW set as required by application for DDC1
Two DDCs 4 Real Real 10% × fS 2 0x0200 = 0x22 (two DDCs; I only selected)
0x0201 = 0x02 (chip decimate by 4)
0x0310, 0x0330 = 0x49 (real mixer; 6 dB gain; variable IF;
real output; HB3 + HB2 + HB1 filters)
0x0311 = 0x00 (DDC0 I input = ADC Channel A; DDC0 Q
input = ADC Channel A)
0x0331 = 0x05 (DDC1 I input = ADC Channel B; DDC1 Q
input = ADC Channel B)
0x0316, 0x0317, 0x0318, 0x0319, 0x031A, 0x031B,
0x031D, 0x031E, 0x031F, 0x0320, 0x0321, 0x0322 = FTW
and POW set as required by application for DDC0
0x0336, 0x0337, 0x0338, 0x0339, 0x033A, 0x033B,
0x033D, 0x033E, 0x033F, 0x0340, 0x0341, 0x0342 = FTW
and POW set as required by application for DDC1
Two DDCs 4 Real Complex 20% × fS 4 0x0200 = 0x02 (two DDCs; I/Q selected)
0x0201 = 0x02 (chip decimate by 4)
0x0310, 0x0330 = 0x40 (real mixer; 6 dB gain; variable IF;
complex output; HB2 + HB1 filters)
0x0311 = 0x00 (DDC0 I input = ADC Channel A; DDC0 Q
input = ADC Channel A)
0x0331 = 0x05 (DDC1 I input = ADC Channel B; DDC1 Q
input = ADC Channel B)
0x0316, 0x0317, 0x0318, 0x0319, 0x031A, 0x031B,
0x031D, 0x031E, 0x031F, 0x0320, 0x0321, 0x0322 = FTW
and POW set as required by application for DDC0
0x0336, 0x0337, 0x0338, 0x0339, 0x033A, 0x033B,
0x033D, 0x033E, 0x033F, 0x0340, 0x0341, 0x0342 = FTW
and POW set as required by application for DDC1
Two DDCs 8 Real Real 5% × fS 2 0x0200 = 0x22 (two DDCs; I only selected)
0x0201 = 0x03 (chip decimate by 8)
0x0310, 0x0330 = 0x4A (real mixer; 6 dB gain; variable
IF; real output; HB4 + HB3 + HB2 + HB1 filters)
0x0311 = 0x00 (DDC0 I input = ADC Channel A; DDC0 Q
input = ADC Channel A)
0x0331 = 0x05 (DDC1 I input = ADC Channel B; DDC1 Q
input = ADC Channel B)
0x0316, 0x0317, 0x0318, 0x0319, 0x031A, 0x031B,
0x031D, 0x031E, 0x031F, 0x0320, 0x0321, 0x0322 = FTW
and POW set as required by application for DDC0
0x0336, 0x0337, 0x0338, 0x0339, 0x033A, 0x033B,
0x033D, 0x033E, 0x033F, 0x0340, 0x0341, 0x0342 = FTW
and POW set as required by application for DDC1
Data Sheet AD9208
Rev. 0 | Page 61 of 136
Chip
Application
Layer
Chip
Decimation
Ratio
DDC
Input
Type
DDC
Output
Type
Bandwidth
Per DDC1
No. of Virtual
Converters
Required Register Settings
Four DDCs 8 Real Complex 10% × fS 8 0x0200 = 0x03 (four DDCs; I/Q selected)
0x0201 = 0x03 (chip decimate by 8)
0x0310, 0x0330, 0x0350, 0x0370 = 0x41 (real mixer; 6 dB
gain; variable IF; complex output; HB3 + HB2 + HB1 filters)
0x0311 = 0x00 (DDC0 I input = ADC Channel A; DDC0 Q
input = ADC Channel A)
0x0331 = 0x00 (DDC1 I input = ADC Channel A; DDC1 Q
input = ADC Channel A)
0x0351 = 0x05 (DDC2 I input = ADC Channel B; DDC2 Q
input = ADC Channel B)
0x0371 = 0x05 (DDC3 I input = ADC Channel B; DDC3 Q
input = ADC Channel B)
0x0316, 0x0317, 0x0318, 0x0319, 0x031A, 0x031B,
0x031D, 0x031E, 0x031F, 0x0320, 0x0321, 0x0322 = FTW
and POW set as required by application for DDC0
0x0336, 0x0337, 0x0338, 0x0339, 0x033A, 0x033B,
0x033D, 0x033E, 0x033F, 0x0340, 0x0341, 0x0342 = FTW
and POW set as required by application for DDC1
0x0356, 0x0357, 0x0358, 0x0359, 0x035A, 0x035B,
0x035D, 0x035E, 0x035F, 0x0360, 0x0361, 0x0362 = FTW
and POW set as required by application for DDC2
0x0376, 0x0377, 0x0378, 0x0379, 0x037A, 0x037B,
0x037D, 0x037E, 0x037F, 0x0380, 0x0381, 0x0382 = FTW
and POW set as required by application for DDC3
Four DDCs 8 Real Real 5% × fS 4 0x0200 = 0x23 (four DDCs; I only selected)
0x0201 = 0x03 (chip decimate by 8)
0x0310, 0x0330, 0x0350, 0x0370 = 0x4A (real mixer; 6 dB
gain; variable IF; real output; HB4 + HB3 + HB2 + HB1 filters)
0x0311 = 0x00 (DDC0 I input = ADC Channel A; DDC0 Q
input = ADC Channel A)
0x0331 = 0x00 (DDC1 I input = ADC Channel A; DDC1 Q
input = ADC Channel A)
0x0351 = 0x05 (DDC2 I input = ADC Channel B; DDC2 Q
input = ADC Channel B)
0x0371 = 0x05 (DDC3 I input = ADC Channel B; DDC3 Q
input = ADC Channel B)
0x0316, 0x0317, 0x0318, 0x0319, 0x031A, 0x031B,
0x031D, 0x031E, 0x031F, 0x0320, 0x0321, 0x0322 = FTW
and POW set as required by application for DDC0
0x0336, 0x0337, 0x0338, 0x0339, 0x033A, 0x033B,
0x033D, 0x033E, 0x033F, 0x0340, 0x0341, 0x0342 = FTW
and POW set as required by application for DDC1
0x0356, 0x0357, 0x0358, 0x0359, 0x035A, 0x035B,
0x035D, 0x035E, 0x035F, 0x0360, 0x0361, 0x0362 = FTW
and POW set as required by application for DDC2
0x0376, 0x0377, 0x0378, 0x0379, 0x037A, 0x037B,
0x037D, 0x037E, 0x037F, 0x0380, 0x0381, 0x0382 = FTW
and POW set as required by application for DDC3
AD9208 Data Sheet
Rev. 0 | Page 62 of 136
Chip
Application
Layer
Chip
Decimation
Ratio
DDC
Input
Type
DDC
Output
Type
Bandwidth
Per DDC1
No. of Virtual
Converters
Required Register Settings
Four DDCs 16 Real Complex 5% × fS 8 0x0200 = 0x03 (four DDCs; I/Q selected)
0x0201 = 0x04 (chip decimate by 16)
0x0310, 0x0330, 0x0350, 0x0370 = 0x42 (real mixer; 6 dB
gain; variable IF; complex output; HB4 + HB3 + HB2 +
HB1 filters)
0x0311 = 0x00 (DDC0 I input = ADC Channel A; DDC0 Q
input = ADC Channel A)
0x0331 = 0x00 (DDC1 I input = ADC Channel A; DDC1 Q
input = ADC Channel A)
0x0351 = 0x05 (DDC2 I input = ADC Channel B; DDC2 Q
input = ADC Channel B)
0x0371 = 0x05 (DDC3 I input = ADC Channel B; DDC3 Q
input = ADC Channel B)
0x0316, 0x0317, 0x0318, 0x0319, 0x031A, 0x031B,
0x031D, 0x031E, 0x031F, 0x0320, 0x0321, 0x0322 = FTW
and POW set as required by application for DDC0
0x0336, 0x0337, 0x0338, 0x0339, 0x033A, 0x033B,
0x033D, 0x033E, 0x033F, 0x0340, 0x0341, 0x0342 = FTW
and POW set as required by application for DDC1
0x0356, 0x0357, 0x0358, 0x0359, 0x035A, 0x035B,
0x035D, 0x035E, 0x035F, 0x0360, 0x0361, 0x0362 = FTW
and POW set as required by application for DDC2
0x0376, 0x0377, 0x0378, 0x0379, 0x037A, 0x037B,
0x037D, 0x037E, 0x037F, 0x0380, 0x0381, 0x0382 = FTW
and POW set as required by application for DDC3
1 fS is the ADC sample rate.
Data Sheet AD9208
Rev. 0 | Page 63 of 136
DDC POWER CONSUMPTION
Table 29 describes the typical and maximum DVDD and DRVDD1 power for certain DDC modes; fS = 3 GHz in all cases.
Table 29. DDC Power Consumption for Example Configurations
Number of
DDCs
DDC Decimation
Ratio1
Number of
Lanes (L)
Number of Virtual
Converters (M)
Number of Octets
per frame (F)
DVDD Power (mW) DRVDD1 Power (mW)
Typ Max Typ Max
2 2 8 4 1 615 1190 415 565
2 3 8 4 1 675 1250 310 435
2 4 8 4 1 585 1150 250 370
2 6 4 4 2 590 1145 175 275
2 8 4 4 2 570 1120 145 245
2 12 2 4 4 585 1135 105 205
4 4 8 8 2 745 1350 415 570
4 6 8 8 2 755 1365 305 440
4 8 8 8 2 715 1320 250 370
1 See Table 17 and Table 18 for details on decimation filter selection, the associated alias protected bandwidths, and SNR improvements.
AD9208 Data Sheet
Rev. 0 | Page 64 of 136
SIGNAL MONITOR
The signal monitor block provides additional information about
the signal being digitized by the ADC. The signal monitor
computes the peak magnitude of the digitized signal. This
information can be used to drive an AGC loop to optimize the
range of the ADC in the presence of real-world signals.
The results of the signal monitor block can be obtained either
by reading back the internal values from the SPI port or by
embedding the signal monitoring information into the JESD204B
interface as separate control bits. A global, 24-bit programmable
period controls the duration of the measurement. Figure 102
shows the simplified block diagram of the signal monitor block.
FROM
MEMORY
MAP
DOWN
COUNTER
IS
COUNT = 1?
MAGNITUDE
STORAGE
REGISTER
FROM
INPUT
SIGNAL
MONITOR
HOLDING
REGISTER
LOAD
CLEAR
COMPARE
A > B
LOAD
LOAD
TO SPORT OVER
JESD204B AND
MEMORY MAP
SIGNAL MONITOR
PERIOD REGISTER
(SMPR)
0x0271, 00x272, 0x0273
15547-097
Figure 102. Signal Monitor Block
The peak detector captures the largest signal within the
observation period. The detector only observes the magnitude
of the signal. The resolution of the peak detector is a 13-bit
value, and the observation period is 24 bits and represents
converter output samples. The peak magnitude can be derived
by using the following equation:
Peak Magnitude (dBFS) = 20log(Peak Detector Value/213)
The magnitude of the input port signal is monitored over a
programmable time period, which is determined by the signal
monitor period register (SMPR). The peak detector function is
enabled by setting Bit 1 in the signal monitor control register
(Register 0x0270). The 24-bit SMPR must be programmed
before activating this mode.
After enabling peak detection mode, the value in the SMPR is
loaded into a monitor period timer, which decrements at the
decimated clock rate. The magnitude of the input signal is
compared with the value in the internal magnitude storage
register (not accessible to the user), and the greater of the two
is updated as the current peak level. The initial value of the
magnitude storage register is set to the current ADC input signal
magnitude. This comparison continues until the monitor period
timer reaches a count of 1.
When the monitor period timer reaches a count of 1, the 13-bit
peak level value is transferred to the signal monitor holding
register, which can be read through the memory map or output
through the SPORT over the JESD204B interface. The monitor
period timer is reloaded with the value in the SMPR, and the
countdown restarts. In addition, the magnitude of the first
input sample is updated in the magnitude storage register, and
the comparison and update procedure, as explained previously,
continues.
Data Sheet AD9208
Rev. 0 | Page 65 of 136
SPORT OVER JESD204B
The signal monitor data can also be serialized and sent over the
JESD204B interface as control bits. These control bits must be
deserialized from the samples to reconstruct the statistical data.
The signal control monitor function is enabled by setting Bits[1:0]
of Register 0x0279 and Bit 1 of Register 0x027A. Figure 103 shows
two different example configurations for the signal monitor
control bit locations inside the JESD204B samples. A maximum
of three control bits can be inserted into the JESD204B samples;
however, only one control bit is required for the signal monitor.
Control bits are inserted from MSB to LSB. If only one control bit
is to be inserted (CS = 1), only the most significant control bit is
used (see Example Configuration 1 and Example Configuration 2
in Figure 103). To select the SPORT over JESD204B option,
program Register 0x0559, Register 0x055A, and Register 0x058F.
See Table 46 for more information on setting these bits.
Figure 104 shows the 25-bit frame data that encapsulates the
peak detector value. The frame data is transmitted MSB first
with five 5-bit subframes. Each subframe contains a start bit
that can be used by a receiver to validate the deserialized data.
Figure 105 shows the SPORT over JESD204B signal monitor
data with a monitor period timer set to 80 samples.
15
14-BIT CONVERTER RESOLUTION (N = 14)
TAIL
X
1
CONTROL
BIT
(CS = 1)
1-BIT
CONTROL
BIT
(CS = 1)
14131211109876543210
1514131211109876543210
1 TAIL
BIT
SERIALIZED SIGNAL MONITOR
FRAME DATA
EXAMPLE
CONFIGURATION 1
(N' = 16, N = 15, CS = 1)
EXAMPLE
CONFIGURATION 2
(N' = 16, N = 14, CS = 1)
SERIALIZED SIGNAL MONITOR
FRAME DATA
16-BIT JESD204B SAMPLE SIZE (N' = 16)
S[13]
X
S[12]
X
S[11]
X
S[10]
X
S[9]
X
S[8]
X
S[7]
X
S[6]
X
S[5]
X
S[4]
X
S[3]
X
S[2]
X
S[1]
X
S[0]
X
CTRL
[BIT 2]
X
CTRL
[BIT 2]
X
S[14]
X
S[13]
X
S[12]
X
S[11]
X
S[10]
X
S[9]
X
S[8]
X
S[7]
X
S[6]
X
S[5]
X
S[4]
X
S[3]
X
S[2]
X
S[1]
X
S[0]
X
15-BIT CONVERTER RESOLUTION (N = 15)
16-BIT JESD204B SAMPLE SIZE (N' = 16)
15547-098
Figure 103. Signal Monitor Control Bit Locations
25-BIT
FRAME
5-BIT IDLE
SUBFRAME
(OPTIONAL)
5-BIT IDENTIFIER
SUBFRAME
5-BIT DATA
MSB
SUBFRAME
5-BIT DATA
SUBFRAME
5-BIT DATA
SUBFRAME
5-BIT DATA
LSB
SUBFRAME
5-BIT SUBFRAMES
P[x] = PEAK MAGNITUDE VALUE
IDLE
1
IDLE
1
IDLE
1
IDLE
1
IDLE
1
START
0P[0]000
START
0P[4] P[3] P[2] P1]
START
0P[8] P[7] P[6] P5]
START
0P[12] P[11] P[10] P[9]
START
0
ID[3]
0
ID[2]
0
ID[1]
0
ID[0]
1
15547-099
Figure 104. SPORT over JESD204B Signal Monitor Frame Data
AD9208 Data Sheet
Rev. 0 | Page 66 of 136
PAYLOAD
25-BIT FRAME (N)
PAYLOAD
25-BIT FRAME (N + 1)
PAYLOAD
25-BIT FRAME (N + 2)
IDLE IDLE IDLE IDLE IDLE IDLEIDLE IDLE IDLE IDLE IDLEIDENT. DATA
MSB DATA DATA DATA
LSB
IDLE IDLE IDLE IDLE IDLE IDLEIDLE IDLE IDLE IDLE IDLEIDENT. DATA
MSB DATA DATA DATA
LSB
IDLE IDLE IDLE IDLE IDLE IDLEIDLE IDLE IDLE IDLE IDLEIDENT. DATA
MSB DATA DATA DATA
LSB
SMPR = 80 SAMPLES (0x0271 = 0x50; 0x0272 = 0x00; 0x0273 = 0x00)
80 SAMPLE PERIOD
80 SAMPLE PERIOD
80 SAMPLE PERIOD
15547-100
Figure 105. SPORT over JESD204B Signal Monitor Example with Period = 80 Samples
Data Sheet AD9208
Rev. 0 | Page 67 of 136
DIGITAL OUTPUTS
INTRODUCTION TO THE JESD204B INTERFACE
The AD9208 digital outputs are designed to the JEDEC standard
JESD204B, serial interface for data converters. JESD204B is a
protocol to link the AD9208 to a digital processing device over a
serial interface with lane rates of up to 16 Gbps. The benefits of
the JESD204B interface over LVDS include a reduction in
required board area for data interface routing and an ability to
enable smaller packages for converter and logic devices.
JESD204B OVERVIEW
The JESD204B data transmit block assembles the parallel data
from the ADC into frames and uses 8-bit/10-bit encoding as
well as optional scrambling to form serial output data. Lane
synchronization is supported through the use of separate
control characters during the initial establishment of the link.
Additional control characters are embedded in the data stream
to maintain synchronization thereafter. A JESD204B receiver is
required to complete the serial link. For additional details on
the JESD204B interface, refer to the JESD204B standard.
The AD9208 JESD204B data transmit block maps up to two
physical ADCs or up to eight virtual converters (when DDCs are
enabled) over a link. A link can be configured to use one, two,
four, or eight JESD204B lanes. The JESD204B specification refers
to a number of parameters to define the link, and these parameters
must match between the JESD204B transmitter (the AD9208
output) and the JESD204B receiver (the logic device input).
The JESD204B link is described according to the following
parameters:
L is the number of lanes per converter device (lanes per
link); AD9208 value = 1, 2, 4, or 8.
M is the number of converters per converter device (virtual
converters per link); AD9208 value = 1, 2, 4, or 8.
F is the octets per frame; AD9208 value = 1, 2, 4, 8, or 16.
N΄ is the number of bits per sample (JESD204B word size);
AD9208 value = 8 or 16.
N is the converter resolution; AD9208 value = 7 to 16.
CS is the number of control bits per sample;
AD9208 value = 0, 1, 2, or 3.
K is the number of frames per multiframe;
AD9208 value = 4, 8, 12, 16, 20, 24, 28, or 32.
S is the samples transmitted per single converter per frame
cycle; AD9208 value is set automatically based on L, M, F,
and N΄.
HD is the high density mode; the AD9208 mode is set
automatically based on L, M, F, and N΄.
CF is the number of control words per frame clock cycle
per converter device; AD9208 value = 0.
Figure 106 shows a simplified block diagram of the AD9208
JESD204B link. By default, the AD9208 is configured to use
two converters and four lanes. Converter A data is output to
SERDOUT0± and/or SERDOUT1±, and Converter B is output
to SERDOUT2± and/or SERDOUT3±. The AD9208 allows
other configurations such as combining the outputs of both
converters onto a single lane, or changing the mapping of the
A and B digital output paths. These modes are set up via a quick
configuration register in the SPI register map, along with
additional customizable options.
By default in the AD9208, the 14-bit converter word from each
converter is broken into two octets (eight bits of data). Bit 13
(MSB) through Bit 6 are in the first octet. The second octet
contains Bit 5 through Bit 0 (LSB) and two tail bits. The tail bits
can be configured as zeros or as a pseudorandom number
sequence. The tail bits can also be replaced with control bits
indicating overrange, SYSREF±, or fast detect output.
The two resulting octets can be scrambled. Scrambling is
optional; however, it is recommended to avoid spectral peaks
when transmitting similar digital data patterns. The scrambler
uses a self synchronizing, polynomial-based algorithm defined
by the equation 1 + x14 + x15. The descrambler in the receiver is
a self synchronizing version of the scrambler polynomial.
The two octets are then encoded with an 8-bit/10-bit encoder. The
8-bit/10-bit encoder works by taking eight bits of data (an octet)
and encoding them into a 10-bit symbol. Figure 107 shows how
the 14-bit data is taken from the ADC, how the tail bits are added,
how the two octets are scrambled, and how the octets are encoded
into two 10-bit symbols. Figure 107 shows the default data format.
MUX/
FORMAT
(SPI
REGISTERS
0x0561,
0x0564)
JESD204B LINK
CONTROL
(L, M, F)
(SPI REGISTER
0x058B,
0x058E, 0x058C)
LANE MUX
AND
MAPPING
(SPI
REGISTERS
0x05B0,
0x05B2,
0x05B3,
0x05B5,
0x05B6)
CONVERTER A
INPUT ADC A
CONVERTER B
CONVERTER 0
CONVERTER 1
INPUT
SYSREF±
SERDOUT0±
SERDOUT7±
SERDOUT6±
SERDOUT5±
SERDOUT4±
SERDOUT3±
SERDOUT2±
SERDOUT1±
SYNCINB±
ADC B
15547-101
Figure 106. Transmit Link Simplified Block Diagram Showing Full Bandwidth Mode (Register 0x0200 = 0x00)
AD9208 Data Sheet
Rev. 0 | Page 68 of 136
ADC TEST PATTERNS
(0x0550,
0x0551 TO 0x0558)
JESD204B LONG
TRANSPORT TEST
PATTERN
0x0571[5]
JESD204B
INTERFACE TEST
PATTERN
(0x0573,
0x0551 TO 0x0558)
JESD204B DATA
LINK LAYER TEST
PATTERNS
0x0574[2:0]
JESD204B SAMPLE
CONSTRUCTION
TAIL BITS
0x0571[6]
A13MSB
LSB
A12
A11
A10
A9
A8
A7
A13
A12
A11
A10
A9
A8
A7
A5
A4
A3
A2
A1
A0
C2
A6
MSB
LSB T
A6
A5
A4
A3
A2
A1
A0
C2
C1CONTROL BITS
C0
ADC
SERDOUT0±
SERDOUT3±
SERDOUT2±
SERDOUT1±
FRAME
CONSTRUCTION
SERIALIZER
SYMBOL0 SYMBOL1
SCRAMBLER
1 + x
14
+ x
15
(OPTIONAL)
OCTET0
OCTET1
S7
S6
S5
S4
S3
S2
S1
S0
S7
a b i j a b i j
a b c d e f g h i j
a b c d e f g h i j
S6
S5
S4
S3
S2
S1
S0
MSB
LSB
8-BIT/
10-BIT
ENCODER
OCTET0
OCTET1
15547-102
Figure 107. ADC Output Datapath Showing Data Framing
SYSREF±
SYNCINB±
PROCESSED
SAMPLES
FROM ADC
SAMPLE
CONSTRUCTION
FRAME
CONSTRUCTION
8-BIT/10-BIT
ENCODER
CROSSBAR
MUX
SCRAMBLER SERIALIZER Tx
ALIGNMENT
CHARACTER
GENERATION
OUTPUT
TRANSPORT
LAYER
DATA LINK
LAYER
PHYSICAL
LAYER
15547-103
Figure 108. Data Flow
FUNCTIONAL OVERVIEW
The block diagram in Figure 108 shows the flow of data through
the JESD204B hardware from the sample input to the physical
output. The processing can be divided into layers that are
derived from the open source initiative (OSI) model widely
used to describe the abstraction layers of communications
systems. These layers are the transport layer, data link layer,
and physical layer (serializer and output driver).
Transport Layer
The transport layer handles packing the data (consisting of
samples and optional control bits) into JESD204B frames that
are mapped to 8-bit octets. These octets are sent to the data link
layer. The transport layer mapping is controlled by rules derived
from the link parameters. Tail bits are added to fill gaps where
required. The following equation can be used to determine the
number of tail bits within a sample (JESD204B word):
T = N΄ – N – CS
Data Link Layer
The data link layer is responsible for the low level functions
of passing data across the link. These functions include optionally
scrambling the data, inserting control characters for multichip
synchronization/lane alignment/monitoring, and encoding
8-bit octets into 10-bit symbols. The data link layer is also
responsible for sending the initial lane alignment sequence
(ILAS), which contains the link configuration data used by the
receiver to verify the settings in the transport layer.
Physical Layer
The physical layer consists of the high speed circuitry clocked at
the serial clock rate. In this layer, parallel data is converted into
one, two, or four lanes of high speed differential serial data.
JESD204B LINK ESTABLISHMENT
The AD9208 JESD204B transmitter (Tx) interface operates in
Subclass 1 as defined in the JEDEC Standard 204B (July 2011
specification). The link establishment process is divided into the
following steps: code group synchronization and SYNCINB±,
initial lane alignment sequence, and user data and error correction.
Code Group Synchronization (CGS) and SYNCINB±
The CGS is the process by which the JESD204B receiver finds
the boundaries between the 10-bit symbols in the stream of
data. During the CGS phase, the JESD204B transmit block
transmits /K28.5/ characters. The receiver must locate /K28.5/
characters in its input data stream using clock and data recovery
(CDR) techniques.
The receiver issues a synchronization request by asserting the
SYNCINB± pin of the AD9208 low. The JESD204B Tx then begins
sending /K/ characters. After the receiver synchronizes, it waits for
the correct reception of at least four consecutive /K/ symbols. It
then deasserts SYNCINB±. The AD9208 then transmits an ILAS
on the following LMFC boundary.
For more information on the code group synchronization
phase, refer to the JEDEC Standard JESD204B, July 2011,
Section 5.3.3.1.
Data Sheet AD9208
Rev. 0 | Page 69 of 136
The SYNCINB± pin operation can also be controlled by the
SPI. The SYNCINB± signal is a differential dc-coupled LVDS
mode signal by default, but it can also be driven single-ended.
For more information on configuring the SYNCINB± pin
operation, refer to Register 0x0572.
The SYNCINB± pins can also be configured to run in CMOS
(single-ended) mode, by setting Bit 4 in Register 0x0572. When
running SYNCINB± in CMOS mode, connect the CMOS
SYNCINB signal to Pin N13 (SYNCINB+) and leave Pin R13
(SYNCINB−) oating.
Initial Lane Alignment Sequence (ILAS)
The ILAS phase follows the CGS phase and begins on the next
LMFC boundary. The ILAS consists of four multiframes, with
an /R/ character marking the beginning and an /A/ character
marking the end. The ILAS begins by sending an /R/ character
followed by 0 to 255 ramp data for one multiframe. On the
second multiframe, the link configuration data is sent, starting
with the third character. The second character is a /Q/ character
to confirm that the link configuration data is to follow. All
undefined data slots are filled with ramp data. The ILAS
sequence is never scrambled.
The ILAS sequence construction is shown in Figure 109. The
four multiframes include the following:
Multiframe 1 begins with an /R/ character (/K28.0/) and
ends with an /A/ character (/K28.3/).
Multiframe 2 begins with an /R/ character followed by a
/Q/ character (/K28.4/), followed by link configuration
parameters over 14 configuration octets (see Table 30) and
ends with an /A/ character. Many of the parameter values
are of the value − 1 notation.
Multiframe 3 begins with an /R/ character (/K28.0/) and
ends with an /A/ character (/K28.3/).
Multiframe 4 begins with an /R/ character (/K28.0/) and
ends with an /A/ character (/K28.3/).
User Data and Error Detection
After the initial lane alignment sequence is complete, the user
data is sent. Normally, within a frame, all characters are considered
user data. However, to monitor the frame clock and multiframe
clock synchronization, there is a mechanism for replacing
characters with /F/ or /A/ alignment characters when the data
meets certain conditions. These conditions are different for
unscrambled and scrambled data. The scrambling operation is
enabled by default; however, it can be disabled using the SPI.
For scrambled data, any 0xFC character at the end of a frame
is replaced by an /F/, and any 0x7C character at the end of a
multiframe is replaced by an /A/. The JESD204B receiver (Rx)
checks for /F/ and /A/ characters in the received data stream
and verifies that they only occur in the expected locations. If an
unexpected /F/ or /A/ character is found, the receiver handles
the situation by using dynamic realignment or asserting the
SYNCINB± signal for more than four frames to initiate a
resynchronization. For unscrambled data, if the final character
of two subsequent frames is equal, the second character is
replaced with an /F/ if it is at the end of a frame, and an /A/ if
it is at the end of a multiframe.
Insertion of alignment characters can be modified using the
SPI. The frame alignment character insertion (FACI) is enabled
by default. More information on the link controls is available in
the Memory Map section, Register 0x0571.
8-Bit/10-Bit Encoder
The 8-bit/10-bit encoder converts 8-bit octets into 10-bit symbols
and inserts control characters into the stream when needed.
The control characters used in JESD204B are shown in Table 30.
The 8-bit/10-bit encoding ensures that the signal is dc balanced by
using the same number of ones and zeros across multiple symbols.
The 8-bit/10-bit interface has options that can be controlled via the
SPI. These operations include bypass and invert. These options are
troubleshooting tools for the verification of the digital front end
(DFE). See the Memory Map section, Register 0x0572, Bits[2:1]
for information on configuring the 8-bit/10-bit encoder.
K K R D
START OF
ILAS
D A R Q D A R D D A R D D
END OF
MULTIFRAME
A DC C D
START OF LINK
CONFIGURATION DATA
START OF
USER DATA
15547-104
Figure 109. Initial Lane Alignment Sequence
Table 30. AD9208 Control Characters used in JESD204B
Abbreviation Control Symbol 8-Bit Value
10-Bit Value,
RD1 = −1
10-Bit Value,
RD1 = +1 Description
/R/ /K28.0/ 000 11100 001111 0100 110000 1011 Start of multiframe
/A/ /K28.3/ 011 11100 001111 0011 110000 1100 Lane alignment
/Q/ /K28.4/ 100 11100 001111 0100 110000 1101 Start of link configuration data
/K/ /K28.5/ 101 11100 001111 1010 110000 0101 Group synchronization
/F/ /K28.7/ 111 11100 001111 1000 110000 0111 Frame alignment
1 RD means running disparity.
AD9208 Data Sheet
Rev. 0 | Page 70 of 136
SERDOUTx+
DRVDD
SERDOUTx–
OUTPUT SWING = 0.85 × DRVDD1 V p-p DIFFERENTIAL
ADJUSTABLE TO
1 × DRVDD1, 0.75 × DRVDD1
100
0.1µF
0.1µF RECEIVER
100
DIFFERENTIAL
TRACE PAIR
15547-105
Figure 110. AC-Coupled Digital Output Termination Example
PHYSICAL LAYER (DRIVER) OUTPUTS
Digital Outputs, Timing, and Controls
The AD9208 physical layer consists of drivers that are defined in
the JEDEC Standard JESD204B, July 2011. The differential digital
outputs are powered up by default. The drivers use a dynamic
100 internal termination to reduce unwanted reflections.
Place a 100 Ω differential termination resistor at each receiver
input to result in a nominal 0.85 × DRVDD1 V p-p swing at the
receiver (see Figure 110). The swing is adjustable through the
SPI registers. AC coupling is recommended to connect to the
receiver. See the Memory Map section (Register 0x05C0 to
Register 0x05C3 in Table 46) for more details.
The AD9208 digital outputs can interface with custom ASICs
and field programmable gate array (FPGA) receivers, providing
superior switching performance in noisy environments. Single
point-to-point network topologies are recommended with a
single differential 100 termination resistor placed as close to
the receiver inputs as possible.
If there is no far end receiver termination, or if there is poor
differential trace routing, timing errors can result. To avoid such
timing errors, it is recommended that the trace length be less
than six inches, and that the differential output traces be close
together and at equal lengths.
Figure 111 to Figure 113 show an example of the digital output
data eye, jitter histogram, and bathtub curve for one AD9208
lane running at 16 Gbps. The format of the output data is twos
complement by default. To change the output data format, see
the Memory Map section (Register 0x0561 in Table 46).
15547-106
Figure 111. Digital Outputs Data Eye, External 100 Ω Terminations at 16 Gbps
15547-107
Figure 112. Digital Outputs Jitter Histogram, External 100 Ω Terminations at
16 Gbps
15547-108
Figure 113. Digital Outputs Bathtub Curve, External 100 Ω Terminations at
16 Gbps
De-Emphasis
De-emphasis enables the receiver eye diagram mask to be met
in conditions where the interconnect insertion loss does not
meet the JESD204B specification. Use the de-emphasis feature
only when the receiver is unable to recover the clock due to
excessive insertion loss. Under normal conditions, it is disabled
to conserve power. Additionally, enabling and setting too high a
de-emphasis value on a short link can cause the receiver eye
diagram to fail. Use the de-emphasis setting with caution
because it can increase electromagnetic interference (EMI). See
the Memory Map section (Register 0x05C4 to Register 0x05CB
in Table 46) for more details.
Phase-Locked Loop (PLL)
The PLL generates the serializer clock, which operates at the
JESD204B lane rate. The status of the PLL lock can be checked
in the PLL locked status bit (Register 0x056F, Bit 7). This read
only bit notifies the user if the PLL achieved a lock for the
specific setup. Register 0x056F also has a loss of lock (LOL)
sticky bit (Bit 3) that notifies the user that a loss of lock is
detected. The sticky bit can be reset by issuing a JESD204B link
restart (Register 0x0571 = 0x15, followed by Register 0x0571 =
0x14). Refer to Table 32 for the reinitialization of the link
following a link power cycle.
The JESD204B lane rate control, Bits[7:4] of Register 0x056E,
must be set to correspond with the lane rate. Table 31 shows the
lane rates supported by the AD9208 using Register 0x056E.
Table 31. AD9208 Register 0x056E Supported Lane Rates
Value Lane Rate
0x00 Lane rate = 6.75 Gbps to 13.5 Gbps
0x10 Lane rate = 3.375 Gbps to 6.75 Gbps
0x30 Lane rate = 13.5 Gbps to 15.5 Gbps (default for AD9208)
0x50 Lane rate = 1.6875 Gbps to 3.375 Gbps
Data Sheet AD9208
Rev. 0 | Page 71 of 136
fS × 4 MODE
fS × 4 mode adds a separate packing mode on top of a JESD204B
transmitter/receiver to fix the serial lane rate at four times the
sample rate (fS).
The JESD204B link settings are
L = 8
M = 2
F = 2
S = 5
N’ = 12
N = 12
CS = 0
CF = 2
HD = 1
However, CF = 2 is not supported by the design; therefore, the
following link parameters are used along with separate packing:
L = 8
M = 2
F = 2
S = 4
N’ = 16
N = 16
CS = 0
CF = 0
HD = 0
In fS × 4 mode, five 12-bit ADC samples (along with an extra
4 bits) are packed into four 16-bit JESD204B samples to create a
64-bit frame.
The following SPI writes are necessary to place the device in fS × 4
mode:
Register 0x0570 = 0xFE. This setting places the device in M =
2, L = 8, fS × 4 mode.
Register 0x058B = 0x0F. This setting places the device CS =
0, N’ = 16 mode.
Register 0x058F = 0x2F. This setting places the device in
Subclass 1 mode, N = 16.
The transmit architecture of fS × 4 mode is shown in Figure 114
and the receive portion is shown in Figure 115. fS × 4 mode only
works in full bandwidth mode (Register 0x0200 = 0x00).
ADC1 SAMPLE N (12 BITS)
CONVERTER 1
SAMPLE N (16 BITS)
CONVERTER 1
SAMPLE N+1 (16 BITS)
CONVERTER 1
SAMPLE N+2 (16 BITS)
CONVERTER 1
SAMPLE N+3 (16 BITS)
S[N][15:0] S[N + 1][15:0] S[N + 2][15:0] S[N + 3][15:0]
JESD204B FRAMER + PHY
(M = 2; L = 8; S = 4; F = 2; N = 16; N’ = 16; CF = 0; HD = 0)
A
PPLICATION
LAYER
TRANSPORT,
DATA LINK,
AND PHY
LAYERS
12-BITS
AT
f
S
LANE 0 LANE 1 LANE 2 LANE 3 LANE 4 LANE 5 LANE 6 LANE 7
f
S
× 4 MODE (TRANSMIT)
1/5 RATE EXCHANGE
ADC1
SAMPLE N (1 2 B ITS)
ADC1
SAMPLE N + 1 (12 BITS)
ADC1
SAMPLE N + 2 (12 BITS)
ADC1
SAMPLE N + 3 (12 BITS)
ADC1
SAMPLE N + 4 (12 BITS) (4 BITS)
S[N][11:0], S[N + 1][11:8]
(16 BITS)
S[N + 1][7:0], S[N + 2][11:4]
(16 BITS)
S[N + 2][3:0 ], S[N + 3][11:0 ]
(16 BITS)
S[N + 4][11:0], 0000
(16 BITS)
ADC0 SAMPLE N (12 BITS)
ADC0
CONVERTER 0
SAMPLE N (16 BITS)
CONVERTER 0
SAMPLE N + 1 (16 BITS)
CONVERTER 0
SAMPLE N + 2 (16 BITS)
CONVERTER 0
SAMPLE N + 3 (16 BITS)
S[N][15:0] S[N + 1][15:0] S[N + 2][15:0] S[N + 3][15:0]
1/5 RATE EXCHANGE
ADC0
SAMPLE N (12 BITS)
ADC0
SAMPLE N + 1 (12 BITS)
ADC0
SAMPLE N + 2 (12 BITS)
ADC0
SAMPLE N + 3 (12 BITS)
ADC0
SAMPLE N + 4 (12 BITS) (4 BITS)
S[N][11:0], S[N + 1][11:8]
(16 BITS)
0000
S[N + 1][7:0], S[N + 2][11:4]
(16 BITS)
S[N + 2][3:0], S[N + 3][11:0]
(16 BITS)
S[N + 4][11:0], 0000
(16 BITS)
0000
ADC1
64-BITS
AT f
S
/5
64-BITS
AT f
S
/5
15547-109
Figure 114. fS × 4 Mode (Transmit)
fS
× 4 MODE (RECEIVE)
APPLICATION
LAYER
DATA LINK,
TRANSPORT,
AND PHY
LAYERS
USER APPLICATION
S[N][15:0] S[N + 1][15:0] S[N + 2][15:0] S[N + 3][15:0]S[N][15:0] S[N + 1][15:0] S[N + 2][15:0] S[N + 3][15:0]
JESD204B FRAMER + PHY
(M = 2; L = 8; S = 4; F = 2; N = 16; N’ = 16; CF = 0; HD = 0)
LANE 0 LANE 1 LANE 2 LANE 3 LANE 4 LANE 5 LANE 6 LANE 7
CONVERTER 1
SAMPLE N (16 BITS)
CONVERTER 1
SAMPLE N + 1 (16 BITS)
CONVERTER 1
SAMPLE N + 2 (16 BITS)
CONVERTER 1
SAMPLE N + 3 (16 BITS)
CONVERTER 0
SAMPLE N (16 BITS)
CONVERTER 0
SAMPLE N + 1 (16 BITS)
CONVERTER 0
SAMPLE N + 2 (16 BITS)
CONVERTER 0
SAMPLE N + 3 (16 BITS)
ADC1
SAMPLE N (12 BITS)
ADC1
SAMPLE N + 1 (12 BITS)
ADC1
SAMPLE N + 2 (12 BITS)
ADC1
SAMPLE N + 3 (12 BITS)
ADC1
SAMPLE N + 4 (12 BITS) (4 BITS)
S[N][11:0], S[N + 1][11:8]
(16 BITS)
S[N + 1][7:0], S[N + 2][11:4]
(16 BITS)
S[N + 2][3:0], S[N + 3][11:0]
(16 BITS)
S[N + 4][11:0], 0000
(16 BITS)
ADC0
SAMPLE N (12 BITS)
ADC0
SAMPLE N + 1 (12 BITS)
ADC0
SAMPLE N + 2 (12 BITS)
ADC0
SAMPLE N + 3 (12 BITS)
ADC0
SAMPLE N + 4 (12 BITS) (4 BITS)
S[N][11:0], S[N + 1][11:8]
(16 BITS)
S[N + 1][7:0], S[N + 2][11:4]
(16 BITS)
S[N + 2][3:0], S[N + 3][11:0]
(16 BITS)
S[N + 4][11:0], 0000
(16 BITS)
64-BITS
AT f
S
/5
64-BITS
AT f
S
/5
0000 0000
15547-110
Figure 115. fS × 4 Mode (Receive)
AD9208 Data Sheet
Rev. 0 | Page 72 of 136
SETTING UP THE AD9208 DIGITAL INTERFACE
To ensure proper operation of the AD9208 at startup, some SPI
writes are required to initialize the link. Additionally, these
registers must be written every time the ADC is reset. Any one
of the following resets warrants the initialization routine for the
digital interface:
Hard reset, as with power-up.
Power-up using the PDWN pin.
Power-up using the SPI via Register 0x0002, Bits[1:0].
SPI soft reset by setting Register 0x0000 = 0x81.
Datapath soft reset by setting Register 0x0001 = 0x02.
JESD204B link power cycle by setting Register 0x0571 =
0x15, then 0x14.
The initialization SPI writes are as shown in Table 32.
Table 32. AD9208 JESD204B Initialization
Register Value Comment
0x1228 0x4F Reset JESD204B start-up circuit
0x1228 0x0F JESD204B start-up circuit in normal operation
0x1222 0x00 JESD204B PLL force normal operation
0x1222 0x04 Reset JESD204B PLL calibration
0x1222 0x00 JESD204B PLL normal operation
0x1262 0x08 Clear loss of lock bit
0x1262 0x00 Loss of lock bit normal operation
The AD9208 has one JESD204B link. The serial outputs
(SERDOUT0± to SERDOUT7±) are considered to be part of
one JESD204B link. The basic parameters that determine the
link setup are
Number of lanes per link (L)
Number of converters per link (M)
Number of octets per frame (F)
If the internal DDCs are used for on-chip digital processing, M
represents the number of virtual converters. The virtual converter
mapping setup is shown in Figure 77.
The maximum lane rate allowed by the AD9208 is 16 Gbps. The
lane rate is related to the JESD204B parameters using the
following equation:
Lane Rate =
L
fNM
OUT
8
10
'
where fOUT = RatioDecimation
fCLOCKADC _
The decimation ratio (DCM) is the parameter programmed in
Register 0x201.
Use the following procedure to configure the output:
1. Power down the link.
2. Select the JESD204B link configuration options.
3. Configure the detailed options.
4. Set output lane mapping (optional).
5. Set additional driver configuration options (optional).
6. Power up the link.
7. Initialize the JESD204B link by issuing the commands
described in Table 32.
If the lane rate calculated is less than 6.25 Gbps, select the low
lane rate option by programming a value of 0x10 to
Register 0x056E.
Table 33 and Table 34 show the JESD204B output configurations
supported for both N΄ = 16 and N΄ = 8 for a given number of
virtual converters. Take care to ensure that the serial lane rate
for a given configuration is within the supported range of
3.4 Gbps to 16 Gbps.
Table 33. JESD204B Output Congurations for N΄ = 161
Number of
Virtual
Converters
Supported
(Same as M)
JESD204B
Serial
Lane
Rate2
Supported Decimation Rates
JESD204B Transport Layer Settings3
Lane Rate =
1.7 Gbps to
3.4 Gbps
Lane Rate =
3.4 Gbps to
6.8 Gbps
Lane Rate =
6.8 Gbps to
13.6 Gbps
Lane Rate =
13.6 Gbps to
15.5 Gbps L M F S HD N N' CS K
1 20 × fOUT 2, 4, 5, 6, 8, 10, 12,
20, 24
1, 2, 3, 4, 5, 6, 8,
10, 12
1, 2, 3, 4, 5, 6, 8 1, 2, 3, 4 1 1 2 1 0 8 to 16 16 0 to
3
See
Note 4
20 × fOUT 2, 4, 5, 6, 8, 10, 12,
20, 24
1, 2, 3, 4, 5, 6, 8,
10, 12
1, 2, 3, 4, 5, 6, 8 1, 2, 3, 4 1 1 4 2 0 8 to 16 16 0 to
3
See
Note 4
10 × fOUT 1, 2, 3, 4, 5, 6, 8,
10, 12
1, 2, 3, 4, 5, 6, 8 1, 2, 3, 4 1, 2 2 1 1 1 1 8 to 16 16 0 to
3
See
Note 4
10 × fOUT 1, 2, 3, 4, 5, 6, 8,
10, 12
1, 2, 3, 4, 5, 6, 8 1, 2, 3, 4 1, 2 2 1 2 2 0 8 to 16 16 0 to
3
See
Note 4
5 × fOUT 1, 2, 3, 4, 5, 6, 8 1, 2, 3, 4 1, 2 1 4 1 1 2 1 8 to 16 16 0 to
3
See
Note 4
5 × fOUT 1, 2, 3, 4, 5, 6, 8 1, 2, 3, 4 1, 2 1 4 1 2 4 0 8 to 16 16 0 to
3
See
Note 4
2.5 × fOUT 1, 2, 3, 4 1, 2 1 8 1 1 4 1 8 to 16 16 0 to
3
See
Note 4
2.5 × fOUT 1, 2, 3, 4 1, 2 1 8 1 2 8 0 8 to 16 16 0 to
3
See
Note 4
Data Sheet AD9208
Rev. 0 | Page 73 of 136
Number of
Virtual
Converters
Supported
(Same as M)
JESD204B
Serial
Lane
Rate2
Supported Decimation Rates
JESD204B Transport Layer Settings3
Lane Rate =
1.7 Gbps to
3.4 Gbps
Lane Rate =
3.4 Gbps to
6.8 Gbps
Lane Rate =
6.8 Gbps to
13.6 Gbps
Lane Rate =
13.6 Gbps to
15.5 Gbps L M F S HD N N' CS K
2 40 × fOUT 4, 8, 10, 12, 15, 16,
20, 24, 30, 40, 48
2, 4, 5, 6, 8, 10,
12, 15, 16, 20,
24, 30
1, 2, 3, 4, 5, 6, 8,
10, 12, 15, 16
1, 2, 3, 4, 5, 6, 8 1 2 4 1 0 8 to 16 16 0 to
3
See
Note 4
40 × fOUT 4, 8, 10, 12, 15, 16,
20, 24, 30, 40, 48
2, 4, 5, 6, 8, 10,
12, 15, 16, 20,
24, 30
1, 2, 3, 4, 5, 6, 8,
10, 12, 15, 16
1, 2, 3, 4, 5, 6, 8 1 2 8 2 0 8 to 16 16 0 to
3
See
Note 4
20 × fOUT 2, 4, 5, 6, 8, 10, 12,
15, 16, 20, 24, 30
1, 2, 3, 4, 5, 6, 8,
10, 12, 15, 16
1, 2, 3, 4, 5, 6, 8 1, 2, 3, 4 2 2 2 1 0 8 to 16 16 0 to
3
See
Note 4
20 × fOUT 2, 4, 5, 6, 8, 10, 12,
15, 16, 20, 24, 30
1, 2, 3, 4, 5, 6, 8,
10, 12, 15, 16
1, 2, 3, 4, 5, 6, 8 1, 2, 3, 4 2 2 4 2 0 8 to 16 16 0 to
3
See
Note 4
10 × fOUT 1, 2, 3, 4, 5, 6, 8,
10, 12, 15, 16
1, 2, 3, 4, 5, 6, 8 1, 2, 3, 4 1, 2 4 2 1 1 1 8 to 16 16 0 to
3
See
Note 4
10 × fOUT 1, 2, 3, 4, 5, 6, 8,
10, 12, 15, 16
1, 2, 3, 4, 5, 6, 8 1, 2, 3, 4 1, 2 4 2 2 2 0 8 to 16 16 0 to
3
See
Note 4
5 × fOUT 1, 2, 3, 4, 5, 6, 8 1, 2, 3, 4 1, 2 1 8 2 1 2 1 8 to 16 16 0 to
3
See
Note 4
5 × fOUT 1, 2, 3, 4, 5, 6, 8 1, 2, 3, 4 1, 2 1 8 2 2 4 0 8 to 16 16 0 to
3
See
Note 4
4 80 × fOUT 8, 16, 20, 24, 30,
40, 48
4, 8, 10, 12, 16,
20, 24, 30, 40,
48
2, 4, 6, 8, 10, 12,
16, 20, 24, 30
2, 4, 6, 8, 10, 12,
16
1 4 8 1 0 8 to 16 16 0 to
3
See
Note 4
40 × fOUT 4, 8, 10, 12, 15, 16,
20, 24, 30, 40, 48
2, 4, 5, 6, 8, 10,
12, 15, 16, 20,
24, 30
1, 2, 3, 4, 5, 6, 8,
10, 12, 15, 16
1, 2, 3, 4, 5, 6, 8 2 4 4 1 0 8 to 16 16 0 to
3
See
Note 4
40 × fOUT 4, 8, 10, 12, 15, 16,
20, 24, 30, 40, 48
2, 4, 5, 6, 8, 10,
12, 15, 16, 20,
24, 30
1, 2, 3, 4, 5, 6, 8,
10, 12, 15, 16
1, 2, 3, 4, 5, 6, 8 2 4 8 2 0 8 to 16 16 0 to
3
See
Note 4
20 × fOUT 2, 4, 5, 6, 8, 10, 12,
15, 16, 20, 24, 30
1, 2, 3, 4, 5, 6, 8,
10, 12, 15, 16
1, 2, 3, 4, 5, 6, 8 1, 2, 3, 4 4 4 2 1 0 8 to 16 16 0 to
3
See
Note 4
20 × fOUT 2, 4, 5, 6, 8, 10, 12,
15, 16, 20, 24, 30
1, 2, 3, 4, 5, 6, 8,
10, 12, 15, 16
1, 2, 3, 4, 5, 6, 8 1, 2, 3, 4 4 4 4 2 0 8 to 16 16 0 to
3
See
Note 4
10 × fOUT 1, 2, 3, 4, 5, 6, 8,
10, 12, 15, 16
1, 2, 3, 4, 5, 6, 8 1, 2, 3, 4 1, 2 8 4 1 1 1 8 to 16 16 0 to
3
See
Note 4
10 × fOUT 1, 2, 3, 4, 5, 6, 8,
10, 12, 15, 16
1, 2, 3, 4, 5, 6, 8 1, 2, 3, 4 1, 2 8 4 2 2 0 8 to 16 16 0 to
3
See
Note 4
8 160 × fOUT 16, 40, 48 8, 16, 20, 24, 40,
48
4, 8, 12, 16, 20,
24, 40, 48
4, 8, 12, 16, 20,
24
1 8 16 1 0 8 to 16 16 0 to
3
See
Note 4
80 × fOUT 8, 16, 20, 24, 40, 48 4, 8, 10, 12, 16,
20, 24, 40, 48
2, 4, 6, 8, 10, 12,
16, 20, 24
2, 4, 6, 8, 10, 12,
16
2 8 8 1 0 8 to 16 16 0 to
3
See
Note 4
40 × fOUT 4, 8, 10, 12, 16, 20,
24, 40, 48
2, 4, 6, 8, 10, 12,
16, 20, 24
2, 4, 6, 8, 10, 12,
16
2, 4, 6, 8 4 8 4 1 0 8 to 16 16 0 to
3
See
Note 4
40 × fOUT 4, 8, 10, 12, 16, 20,
24, 40, 48
2, 4, 6, 8, 10, 12,
16, 20, 24
2, 4, 6, 8, 10, 12,
16
2, 4, 6, 8 4 8 8 2 0 8 to 16 16 0 to
3
See
Note 4
20 × fOUT 2, 4, 6, 8, 10, 12,
16, 20, 24
2, 4, 6, 8, 10, 12,
16
2, 4, 6, 8 2, 4 8 8 2 1 0 8 to 16 16 0 to
3
See
Note 4
20 × fOUT 2, 4, 6, 8, 10, 12,
16, 20, 24
2, 4, 6, 8, 10, 12,
16
2, 4, 6, 8 2, 4 8 8 4 2 0 8 to 16 16 0 to
3
See
Note 4
1 Due to the internal clock requirements, only certain decimation rates are supported for certain link parameters.
2 JESD204B transport layer descriptions are as follows: L is the number of lanes per converter device (lanes per link); M is the number of virtual converters per converter
device (virtual converters per link); F is the octets per frame; S is the samples transmitted per virtual converter per frame cycle; HD is the high density mode; N is the virtual
converter resolution (in bits); N' is the total number of bits per sample (JESD204B word size); CS is the number of control bits per conversion sample; K is the number of frames per
multiframe.
3 fADC_CLK is the ADC sample rate; DCM = chip decimation ratio; fOUT is the output sample rate = fADC_CLK/DCM; SLR is the JESD204B serial lane rate. The following equations must be
met due to internal clock divider requirements: SLR ≥ 1.6875 Gbps and SLR ≤ 15.5 Gbps; SLR/40 ≤ fADC_CLK; least common multiple (20 × DCM × fOUT/SLR, DCM) ≤ 64. When the SLR
is ≤ 15500 Mbps and > 13500 Mbps, Register 0x056E must be set to 0x30. When the SLR is ≤ 13500 Mbps and ≥ 6750 Mbps, Register 0x056E must be set to 0x00. When the SLR is
< 6750 Mbps and ≥ 3375 Mbps, Register 0x056E must be set to 0x10. When the SLR is < 3375 Mbps and ≥ 1687.5 Mbps, Register 0x056E must be set to 0x50.
4 Only valid K × F values that are divisible by 4 are supported: for F = 1, K = 20, 24, 28, 32; for F = 2, K = 12, 16, 20, 24, 28, 32; for F = 4, K = 8, 12, 16, 20, 24, 28, 32; for F = 8, K = 4,
8, 12, 16, 20, 24, 28, 32; and for F = 16, K = 4, 8, 12, 16, 20, 24, 28, 32.
AD9208 Data Sheet
Rev. 0 | Page 74 of 136
Table 34. JESD204B Output Configurations (N' = 12)1
No. of
Virtual
Converters
Supported
(Same Value
as M)
Serial
Lane
Rate2
Supported
Decimation
Rates for
Lane Rate =
1.7 Gbps to
3.4 Gbps
Supported
Decimation
Rates for
Lane Rate =
3.4 Gbps to
6.8 Gbps
Supported
Decimation
Rates for
Lane Rate =
6.8 Gbps to
13.5 Gbps
Supported
Decimation
Rates for
Lane Rate =
13.5 Gbps
to 15.5 Gbps
JESD204B Transport Layer Settings3
L M F S HD N N' L K
1 15 × fOUT 3, 6, 12 3, 6, 12 3, 6 1 1 3 2 0 8 to 12 12 0 to 3 See
Note 4
7.5 × fOUT 3, 6 3, 6 3 2 1 3 4 1 8 to 12 12 0 to 3 See
Note 4
7.5 × fOUT 3, 6 3, 6 3 2 1 6 8 0 8 to 12 12 0 to 3 See
Note 4
5 × fOUT 1, 2, 3, 4, 5, 6,
8
1, 2, 3, 4 1, 2 1 3 1 1 2 1 8 to 12 12 0 to 3 See
Note 4
2 30 × fOUT 3, 6, 12, 24 3, 6, 12, 24 3, 6, 12 1 2 3 1 0 8 to 12 12 0 to 3 See
Note 4
15 × fOUT 3, 6, 12 3, 6, 12 3, 6 2 2 3 2 0 8 to 12 12 0 to 3 See
Note 4
10 × fOUT 1, 2, 3, 4, 5, 6,
8, 10, 12, 16
1, 2, 3, 4, 5, 6,
8
1, 2, 3, 4 1, 2 3 2 1 1 1 8 to 12 12 0 to 3 See
Note 4
7.5 × fOUT 3, 6 3, 6 3 4 2 3 4 0 8 to 12 12 0 to 3 See
Note 4
4 60 × fOUT 6, 12, 24, 48 3, 6, 12, 24, 48 3, 6, 12, 24 1 4 6 1 0 8 to 12 12 0 to 3 See
Note 4
30 × fOUT 3, 6, 12, 24 3, 6, 12, 24 3, 6, 12 2 4 3 1 0 8 to 12 12 0 to 3 See
Note 4
20 × fOUT 2, 4, 5, 6, 8, 10,
12, 16, 20, 24
1, 2, 3, 4, 5, 6,
8, 10, 12, 16
1, 2, 3, 4, 5,
6, 8
1, 2, 3, 4 3 4 2 1 1 8 to 12 12 0 to 3 See
Note 4
15 × fOUT 3, 6, 12 3, 6, 12 3, 6 4 4 3 2 0 8 to 12 12 0 to 3 See
Note 4
8 60 × fOUT 6, 12, 24, 48 6, 12, 24, 48 6, 12, 24 2 8 6 1 0 8 to 12 12 0 to 3 See
Note 4
30 × fOUT 6, 12, 24 6, 12, 24 6, 12 4 8 3 1 0 8 to 12 12 0 to 3 See
Note 4
1 Due to the internal clock requirements, only certain decimation rates are supported for certain link parameters.
2 fADC_CLK is the ADC sample rate; DCM is the chip decimation ratio; fOUT is the output sample rate = fADC_CLK/DCM; SLR is the JESD204B serial lane rate. The following equations
must be met due to internal clock divider requirements: SLR ≥ 1.6875 Gbps and SLR ≤ 15.5 Gbps; SLR/40 ≤ fADC_CLK; least common multiple (20 × DCM × fOUT/SLR, DCM) ≤ 64.
When the SLR is ≤ 15500 Mbps and > 13500 Mbps, Register 0x056E must be set to 0x30. When the SLR is ≤ 13500 Mbps and ≥ 6750 Mbps, Register 0x056E must be set
to 0x00. When the SLR is < 6750 Mbps and ≥ 3375 Mbps, Register 0x056E must be set to 0x10. When the SLR is < 3375 Mbps and ≥ 1687.5 Mbps, Register 0x056E must
be set to 0x50.
3 JESD204B transport layer descriptions are as follows: L is the number of lanes per converter device (lanes per link); M is the number of virtual converters per converter device
(virtual converters per link); F is the octets per frame; S is the samples transmitted per virtual converter per frame cycle; HD is the high density mode; N is the virtual converter
resolution (in bits); N' is the total number of bits per sample (JESD204B word size); CS is the number of control bits per conversion sample; K is the number of frames per
multiframe.
4 Only valid K × F values that are divisible by 4 are supported: for F = 1, K = 20, 24, 28, 32; for F = 2, K = 12, 16, 20, 24, 28, 32; for F = 4, K = 8, 12, 16, 20, 24, 28, 32; for F = 8, K = 4,
8, 12, 16, 20, 24, 28, 32; and for F = 16, K = 4, 8, 12, 16, 20, 24, 28, 32.
Data Sheet AD9208
Rev. 0 | Page 75 of 136
Table 32. JESD204B Output Congurations for N΄ = 81
No. of
Virtual
Converters
Supported
(Same Value
as M)
Serial
Lane
Rate2
Supported
Decimation
Rates for
Lane Rate =
1.7 Gbps to
3.4 Gbps
Supported
Decimation
Rates for
Lane Rate =
3.4 Gbps to
6.8 Gbps
Supported
Decimation
Rates for
Lane Rate =
6.8 Gbps to
13.5 Gbps
Supported
Decimation
Rates for
Lane Rate =
13.5 Gbps to
15.5 Gbps
JESD204B Transport Layer Settings3
L M F S HD N N' CS K
1 10 × fOUT 1, 2, 3, 4, 5, 6,
8, 10, 12
1, 2, 3, 4, 5,
6, 8
1, 2, 3, 4 1, 2 1 1 1 1 0 7 to 8 8 0 to 1 See
Note 4
1 10 × fOUT 1, 2, 3, 4, 5, 6,
8, 10, 12
1, 2, 3, 4, 5,
6, 8
1, 2, 3, 4 1, 2 1 1 2 2 0 7 to 8 8 0 to 1 See
Note 4
1 5 × fOUT 1, 2, 3, 4, 5, 6,
8
1, 2, 3, 4 1, 2 1 2 1 1 2 0 7 to 8 8 0 to 1 See
Note 4
1 5 × fOUT 1, 2, 3, 4, 5, 6,
8
1, 2, 3, 4 1, 2 1 2 1 2 4 0 7 to 8 8 0 to 1 See
Note 4
1 5 × fOUT 1, 2, 3, 4, 5, 6,
8
1, 2, 3, 4 1, 2 1 2 1 4 8 0 7 to 8 8 0 to 1 See
Note 4
1 2.5 × fOUT 1, 2, 3, 4 1, 2 1 4 1 1 4 0 7 to 8 8 0 to 1 See
Note 4
1 2.5 × fOUT 1, 2, 3, 4 1, 2 1 4 1 2 8 0 7 to 8 8 0 to 1 See
Note 4
2 20 × fOUT 2, 4, 5, 6, 8, 10,
12, 15, 16, 20,
24, 30
1, 2, 3, 4, 5,
6, 8, 10, 12,
15, 16
1, 2, 3, 4, 5,
6, 8
1, 2, 3, 4 1 2 2 1 0 7 to 8 8 0 to 1 See
Note 4
2 10 × fOUT 1, 2, 3, 4, 5, 6,
8, 10, 12, 15,
16
1, 2, 3, 4, 5,
6, 8
1, 2, 3, 4 1, 2 2 2 1 1 0 7 to 8 8 0 to 1 See
Note 4
2 10 × fOUT 1, 2, 3, 4, 5, 6,
8, 10, 12, 15,
16
1, 2, 3, 4, 5,
6, 8
1, 2, 3, 4 1, 2 2 2 2 2 0 7 to 8 8 0 to 1 See
Note 4
2 5 × fOUT 1, 2, 3, 4, 5, 6,
8
1, 2, 3, 4 1, 2 1 4 2 1 2 0 7 to 8 8 0 to 1 See
Note 4
2 5 × fOUT 1, 2, 3, 4, 5, 6,
8
1, 2, 3, 4 1, 2 1 4 2 2 4 0 7 to 8 8 0 to 1 See
Note 4
2 5 × fOUT 1, 2, 3, 4, 5, 6,
8
1, 2, 3, 4 1, 2 1 4 2 4 8 0 7 to 8 8 0 to 1 See
Note 4
1 Due to the internal clock requirements, only certain decimation rates are supported for certain link parameters.
2 fADC_CLK is the ADC sample rate; DCM is the chip decimation ratio; fOUT is the output sample rate = fADC_CLK/DCM; SLR is the JESD204B serial lane rate. The following equations
must be met due to internal clock divider requirements: SLR ≥ 1.6875 Gbps and SLR ≤ 15.5 Gbps; SLR/40 ≤ fADC_CLK; least common multiple (20 × DCM × fOUT/SLR, DCM) ≤ 64.
When the SLR is ≤ 15500 Mbps and > 13500 Mbps, Register 0x056E must be set to 0x30. When the SLR is ≤ 13500 Mbps and ≥ 6750 Mbps, Register 0x056E must be set
to 0x00. When the SLR is < 6750 Mbps and ≥ 3375 Mbps, Register 0x056E must be set to 0x10. When the SLR is < 3375 Mbps and ≥ 1687.5 Mbps, Register 0x056E must
be set to 0x50.
3 JESD204B transport layer descriptions are as follows: L is the number of lanes per converter device (lanes per link); M is the number of virtual converters per converter device
(virtual converters per link); F is the octets per frame; S is the samples transmitted per virtual converter per frame cycle; HD is the high density mode; N is the virtual converter
resolution (in bits); N' is the total number of bits per sample (JESD204B word size); CS is the number of control bits per conversion sample; K is the number of frames per
multiframe.
4 Only valid K × F values that are divisible by 4 are supported: for F = 1, K = 20, 24, 28, 32; for F = 2, K = 12, 16, 20, 24, 28, 32; for F = 4, K = 8, 12, 16, 20, 24, 28, 32; for F = 8, K = 4,
8, 12, 16, 20, 24, 28, 32; and for F = 16, K = 4, 8, 12, 16, 20, 24, 28, 32.
AD9208 Data Sheet
Rev. 0 | Page 76 of 136
Example 1—Full Bandwidth Mode
JESD204B
LINK
(L = 8,
M = 2,
F = 1,
S = 2,
N´ = 16,
N = 16,
CS = 0,
HD = 1)
L
0
M
0
S
0
[15:8]
M
0
S
0
[7:0]
M
0
S
1
[15:8]
M
0
S
1
[7:0]
M
1
S
0
[15:8]
M
1
S
0
[7:0]
M
1
S
1
[15:8]
M
1
S
1
[7:0]
L
1
L
2
L
3
L
4
L
5
L
6
L
7
VIN_A
REAL
I = REAL COMPONENT
Q = QUADRATURE COMPONENT
DCM = DECIMATION
C2R = COMPLEX TO REAL
M
X
= VIRTUAL CONVERTER X
L
Y
= LANE Y
S
Z
= SAMPLE Z INSIDE A JESD204B FRAME
C = CONTROL BIT (OVERRANGE, AMONG OTHERS)
T = TAIL BIT
VIN_B
REAL
M
0
SYNC~
2949.12MSP
S
14745.6MSP
S
F = 1
M
1
14-BIT
ADC
CORE
14-BIT
ADC
CORE
15547-111
Figure 116. Full Bandwidth Mode
The AD9208 is set up as shown in Figure 116, with the following
configurations:
Two 14-bit converters at 2.94912 GSPS.
Full bandwidth application layer mode.
Decimation filters bypassed.
The JESD204B output configuration is as follows:
Two virtual converters required (see Table 33).
Output sample rate (fOUT) = 2949.12/1 = 2949.12 MSPS.
The JESD204B supported output configurations are as follows
(see Table 33):
N΄ = 16 bits.
N = 14 bits.
L = 8, M = 2, and F = 1, or L = 8, M = 2, and F = 2.
CS = 0.
K = 32.
Output serial lane rate = 14.7456 Gbps per lane.
The PLL control register, Register 0x056E, is set to 0x30.
Data Sheet AD9208
Rev. 0 | Page 77 of 136
Example 2—ADC with DDC Option (Two ADCs Plus Two DDCs)
2949.12MSPS 368.64MSPS 7.3728Gbps
F = 2
14-BIT
ADC CORE
DDC 1
(REAL INPUT,
DCM = 8
C2R = BYPASS) M
3
(Q)
M
2
(I)
VIN_B
REAL
14-BIT
ADC CORE
DDC 0
(REAL INPUT,
DCM = 8
C2R = BYPASS)
JESD204B LINK
(L = 4 M = 4 F = 2,
S = 1, N’ = 16, N = 16,
CS = 0, HD = 0)
M
1
(Q)
M
0
(I)
L
0
L
1
L
2
L
3
SYNC~
VIN_A
REAL
M
0
(I)S
0
[15:8]
M
0
(I)S
0
[7:0]
M
1
(Q)S
0
[15:8]
M
1
(Q)S
0
[7:0]
M
2
(I)S
0
[15:8]
M
2
(I)S
0
[7:0]
M
3
(Q)S
0
[15:8]
M
3
(Q)S
0
[7:0]
I = REAL COMPONENT
Q = QUADRATURE COMPONENT
DCM = DECIMATION
C2R = COMPLEX TO REAL
M
X
= VIRTUAL CONVERTER X
L
Y
= LANE Y
S
Z
= SAMPLE Z INSIDE A JESD204B FRAME
C = CONTROL BIT (OVER RANGE, AMONG OTHERS)
T = TAIL BIT
15547-112
Figure 117. Two ADCs Plus Two DDCs Mode (L = 4, M = 4, F = 2, S = 1)
This example shows the flexibility in the digital and lane
configurations for the AD9208. The sample rate is 2.94912 GSPS;
however, the outputs are all combined in either two or four
lanes, depending on the input/output speed capability of the
receiving device.
The AD9208 is set up as shown in Figure 117, with the following
configuration:
Two 14-bit converters at 2.94912 GSPS.
Two DDC application layer mode with complex outputs
(I/Q).
Chip decimation ratio = 8.
DDC decimation ratio = 8 (see Table 46).
The JESD204B output configuration is as follows:
Four virtual converters required (see Table 33).
Output sample rate (fOUT) = 2949.12/8 = 368.64 MSPS.
The JESD204B supported output configurations are as follows
(see Table 33):
N΄ = 16 bits.
N = 14 bits .
L = 2, M = 4, and F = 4, or L = 4, M = 4, and F = 2.
CS = 0.
K = 32.
Output serial lane rate = 14.7456 Gbps per lane (L = 2) or
7.3728 Gbps per lane (L = 4).
For L = 2, set the PLL control register, Register 0x056E, to 0x30.
For L = 4, set the PLL control register, Register 0x056E, to 0x00.
AD9208 Data Sheet
Rev. 0 | Page 78 of 136
DETERMINISTIC LATENCY
Both ends of the JESD204B link contain various clock domains
distributed throughout each system. Data traversing from one
clock domain to a different clock domain can lead to ambiguous
delays in the JESD204B link. These ambiguities lead to non-
repeatable latencies across the link from one power cycle or link
reset to the next. Section 6 of the JESD204B specification
addresses the issue of deterministic latency with mechanisms
defined as Subclass 1 and Subclass 2.
The AD9208 supports JESD204B Subclass 0 and Subclass 1
operation. Register 0x0590, Bits[7:5] set the subclass mode for the
AD9208 and its default is set for Subclass 1 operating mode
(Register 0x0590, Bit 5 = 1). If deterministic latency is not a
system requirement, Subclass 0 operation is recommended and
the SYSREF signal may not be required. Even in Subclass 0
mode, the SYSREF signal may be required in an application
where multiple AD9208 devices must be synchronized with
each other. This topic is addressed in the Timestamp Mode
section.
SUBCLASS 0 OPERATION
If there is no requirement for multichip synchronization while
operating in Subclass 0 mode (Register 0x0590, Bits[7:5]= 0),
the SYSREF input can be left disconnected. In this mode, the
relationship of the JESD204B clocks between the JESD204B
transmitter and receiver are arbitrary, but does not affect the ability
of the receiver to capture and align the lanes within the link.
SUBCLASS 1 OPERATION
The JESD204B protocol organizes data samples into octets, frames,
and multiframes as described in the Transport Layer section.
The LMFC is synchronous with the beginnings of these
multiframes. In Subclass 1 operation, the SYSREF is used to
synchronize the LMFCs for each device in a link or across
multiple links (within the AD9208, SYSREF also synchronizes
the internal sample dividers), as shown in Figure 118. The
JESD204B receiver uses the multiframe boundaries and
buffering to achieve consistent latency across lanes (or even
multiple devices), and also to achieve a fixed latency between
power cycles and link reset conditions.
Deterministic Latency Requirements
Several key factors are required for achieving deterministic
latency in a JESD204B Subclass 1 system.
SYSREF± signal distribution skew within the system must
be less than the desired uncertainty for the system.
SYSREF± setup and hold time requirements must be met
for each device in the system.
The total latency variation across all lanes, links, and
devices must be ≤1 LMFC periods (see Figure 118). This
includes both variable delays and the variation in fixed
delays from lane to lane, link to link, and device to device
in the system.
SYSREF-ALIGNED
GLOBAL LMFC
ALL LMFCs
DATA
DEVICE CLOCK
SYSREF
ILAS DATA
SYSREF TO LMFC DELAY
POWER CYCLE VARIATION
(MUST BE < tLMFC)
15547-113
Figure 118. SYSREF and LMFC
Data Sheet AD9208
Rev. 0 | Page 79 of 136
Setting Deterministic Latency Registers
The JESD204B receiver in the logic device buffers data starting
on the LMFC boundary. If the total link latency in the system is
near an integer multiple of the LMFC period, it is possible that
from one power cycle to the next, the data arrival time at the
receive buffer may straddle an LMFC boundary. To ensure
deterministic latency in this case, a phase adjustment of the
LMFC at either the transmitter or receiver must be performed.
Typically, adjustments to accommodate the receive buffer are
made to the LMFC of the receiver. Alternatively, this adjustment
can be made in the AD9208 using the LMFC offset register
(Register 0x0578, Bits[4:0]). This delays the LMFC in frame
clock increments, depending on the F parameter (number of
octets per lane per frame). For F = 1, every fourth setting (0, 4,
8, and so on) is valid and results in a four frame clock shift. For
F = 2, every other setting (0, 2, 4, and so on) is valid and results
in a two frame clock shift. For all other values of F, each setting
results in a one frame clock shift. Figure 119 shows that, when
the link latency is near an LMFC boundary, the local LMFC of
the AD9208 can be adjusted to delay the data arrival time at the
receiver. Figure 120 shows how the LMFC of the receiver is
delayed to accommodate the receive buffer timing. Consult the
applicable JESD204B receiver user guide for details on making
this adjustment. If the total latency in the system is not near an
integer multiple of the LMFC period or if the appropriate
adjustments have been made to the LMFC phase at the clock
source, it is still possible to have variable latency from one
power cycle to the next. By design, the AD9208 has circuitry in
place to minimize this variation from power-up to power-up. In
this case, the user must check for the possibility that the setup
and hold time requirements for the SYSREF signal are not being
met, by reading the SYSREF setup/hold monitor register
(Register 0x0128). This function is fully described in the
SYSREF± Setup/Hold Window Monitor section.
If reading Register 0x0128 indicates there may be a timing
problem, there are a few adjustments that can made in the
AD9208. Changing the SYSREF level that is used for alignment is
possible using the SYSREF transition select bit (Register 0x0120,
Bit 4). Also, changing which edge of CLK is used to capture
SYSREF can be done using the CLK edge select bit
(Register 0x0120, Bit 3). Both of these options are described in
the SYSREF Control Features section. If neither of these measures
helps to achieve an acceptable setup and hold time, adjusting
the phase of SYSREF and/or the device clock (CLK±) may be
required.
SYSREF-ALIGNED
GLOBAL LMFC
DATA
(AT Tx INPUT)
DATA
(AT Rx INPUT)
Tx LOCAL LMFC
Tx LMFC MOVED (DELAYING THE ARRIVAL OF DATA RELATIVE
TO THE GLOBAL LMFC) SO THE RECIEVE BUFFER RELEASE TIME
IS ALWAYS REFERENCED TO THE SAME LMFC EDGE
LMFC
TX
DELAY TIME POWER CYCLE VARIATION
ILAS DATA
ILAS DATA
15547-114
Figure 119. Adjusting the JESD204B Tx LMFC in the AD9208
DATA
POWER CYCLE VARIATIONLMFC
RX
DELAY TIM
E
ILAS ILAS
ILAS
S
YSREF-ALIGNED
GLOBAL LMFC
DATA
(AT Tx INPUT)
DATA
(AT Rx INPUT)
Rx LOCAL LMFC
Rx LMFC MOVED SO THE RECEIVE BUFFER RELEASE TIME
IS ALWAYS REFERENCED TO THE SAME LMFC EDGE
15547-115
DATA
Figure 120. Adjusting the JESD204B Rx LMFC in the Logic Device
AD9208 Data Sheet
Rev. 0 | Page 80 of 136
MULTICHIP SYNCHRONIZATION
The flowchart in Figure 122 shows the internal mechanism for
multichip synchronization in the AD9208. There are two methods
by which multichip synchronization can take place, as determined
by the chip synchronization mode bit (Register 0x01FF, Bit 0).
Each method involves different applications of the SYSREF signal.
NORMAL MODE
The default sate of the chip synchronization mode bit is 0, which
configures the AD9208 for normal chip synchronization. The
JESD204B standard specifies the use of SYSREF to provide for
deterministic latency within a single link. This same concept,
when applied to a system with multiple converters and logic
devices can also provide multichip synchronization. In Figure 122,
this is referred to as normal mode. Following the process in the
flowchart ensures that the AD9208 is configured appropriately. The
user must also consult the logic devices user IP guide to ensure
that the JESD204B receivers are configured appropriately.
TIMESTAMP MODE
For all AD9208 full bandwidth operating modes, the SYSREF
input can also be used to timestamp samples. This is another
method by which multiple channels and multiple devices can
achieve synchronization. This method is especially effective when
synchronizing multiple devices to one or more logic devices. The
logic devices buffer the data streams, identify the timestamped
samples, and align them. When the chip synchronization mode
bit (Register 0x01FF, Bit 0) is set to 1, the timestamp method is
used for synchronization of multiple channels and/or devices.
In this mode, SYSREF resets the sample dividers and the
JESD204B clocking. When the chip sync mode is set to 1, the
clocks are not reset; instead, the coinciding sample is timestamped
using the JESD204B control bits of that sample. To operate in
timestamp mode, these additional settings are necessary:
Continuous or N-shot SYSREF must be enabled
(Register 0x0120, Bits[2:1] = 1 or 2).
At least one control bit must be enabled (Register 0x058F,
Bits[7:6] = 1, 2, or 3).
Set the function for one of the control bits to SYSREF:
Register 0x0559, Bits[3:0] = 5 if using Control Bit 0.
Register 0x0559, Bits[7:4] = 5 if using Control Bit 1.
Register 0x055A, Bits[3:0] = 5 if using Control Bit 2.
Figure 121 shows how the input sample coincident with
SYSREF is timestamped and ultimately output of the ADC. In
this example, there are two control bits, and Control Bit 0 is the
bit indicating which sample was coincident with the SYSREF
rising edge. Note that the pipeline latencies for each channel are
identical. If so desired, the SYSREF timestamp delay register
(Register 0x0123) can be used to adjust the timing of which
sample is time stamped.
Note that time stamping is not supported by any AD9208
operating modes that use decimation.
A
IN
A
A
IN
B
ENCODE CL
K
SYSREF
CHANNEL B
CHANNEL A
N – 1 N
N + 1
N + 2 N + 3
N – 1 N
N + 1
N + 2 N + 3
N – 1 N N + 1
2 CONTROL BITS
CONTROL BIT 0 USED TO
TIME STAMP SAMPLE N
14-BIT SAMPLES OUT
N + 2 N + 300 00 00 0001
N – 1 N N + 1 N + 2 N + 300 00 00 0001
15547-116
Figure 121. AD9208 Timestamping Example—CS = 2 (Register 0x058F, Bits[7:6] = 2), Control Bit 0 is SYSREF (Register 0x0559, Bits[3:0] = 5)
Data Sheet AD9208
Rev. 0 | Page 81 of 136
YES
UPDATE SETUP/HOLD
DETECTOR STATUS
(0x0128)
INCREMENT
SYSREF IGNORE
COUNTER
YES
NO
SYSREF
IGNORE
COUNTER
EXPIRED?
(0x0121)
SYSREF
ENABLED?
(0x0120)
NO
CLOCK
DIVIDER
>1?
(
0x
010B)
YES
INPUT
CLOCK DIVIDER
ALIGNMENT
REQUIRED?
CLOCK
DIVIDER
AUTO ADJUST
ENABLED?
YES
NO NO NO
YES
ALIGN CLOCK
DIVIDER PHASE
TO SYSREF
SYNCHRO-
NIZATION
MODE?
(0x01FF)
TIMESTAMP
MODE
NORMAL
MODE
YES SYSREF INSERTED
IN JESD204B
CONTROL BITS
BACK TO START
BACK TO START
NO
JESD204B
LMFC
ALIGNMENT
REQUIRED?
DDC NCO
ALIGNMENT
ENABLED?
(0x0300)
YES
NO
ALIGN PHASE OF ALL
INTERNAL CLOCKS
(INCLUDING LMFC)
TO SYSREF
SYNC~
ASSERTED
SEND INVALID 8-BIT/
10-BIT CHARACTERS
(ALL 0s)
NO
YES SEND K28.5
CHARACTERS
NORMAL
JESD204B
INITIALIZATION
SYSREF
ENABLED
IN CONTROL BITS?
(0x0559, 0x055A,
0x058F)
RESET
SYSREF IGNORE
COUNTER
START
SYSREF
ASSERTED?
YES
NO
ALIGN DDC NCO
PHASE
ACCUMULATOR
YES
SIGNAL
MONITOR
ALIGNMENT
ENABLED?
(0x026F)
ALIGN SIGNAL
MONITOR
COUNTERS
YES
NO NO
SYSREF RESETS
RAMP TEST MODE
GENERATOR
RAMP
TEST MODE
ENABLED?
(0x0550)
YES
NO
INCREMENT
SYSREF COUNTER
(0x012A)
SYSREF
TIMESTAMP
DELAY
(0x0123)
SYSREF
MODE
(0x0120)
N-SHOT
MODE
CONTINUOUS
MODE
CLEAR SYSREF IGNORE COUNTER
AND DISABLE SYSREF
(CLEAR BIT 2 IN 0x0120)
15547-117
Figure 122. SYSREF Capture Scenarios and Multichip Synchronization
AD9208 Data Sheet
Rev. 0 | Page 82 of 136
SYSREF INPUT
The SYSREF input signal is used as a high accuracy system
reference for deterministic latency and multichip synchro-
nization. The AD9208 accepts a single-shot or periodic input
signal. The SYSREF mode select bits (Register 0x0120, Bits[2:1])
select the input signal type and also arm the SYSREF state
machine when set. If in single (or N) shot mode (Register 0x0120,
Bits[2:1] = 2), the SYSREF mode select bit self clears after the
appropriate SYSREF transition is detected. The pulse width
must have a minimum width of two CLK± periods. If the clock
divider (Register 0x010B, Bits[3:0]) is set to a value other than
divide by 1, multiply this minimum pulse width requirement by
the divide ratio (that is, if set to divide by 8, the minimum pulse
width is 16 CLK± cycles). When using a continuous SYSREF
signal (Register 0x0120, Bits[2:1] = 1), the period of the SYSREF
signal must be an integer multiple of the LMFC. LMFC can be
derived using the following formula:
LMFC = ADC clock/(S × K)
where:
S is the JESD204B parameter for number of samples per converter.
K is the number of frames per multiframe.
The input clock divider, DDCs, signal monitor block, and
JESD204B link are all synchronized using the SYSREF± input when
in normal synchronization mode (Register 0x01FF, Bit 0 = 0).
The SYSREF± input can also be used to timestamp an ADC
sample to provide a mechanism for synchronizing multiple
AD9208 devices in a system. For the highest level of timing
accuracy, SYSREF± must meet setup and hold requirements
relative to the CLK± input. There are several features in the
AD9208 that can be used to ensure these requirements are met;
these features are described in the SYSREF Control Features
section.
SYSREF Control Features
SYSREF is used, along with the input clock (CLK), as part of a
source-synchronous timing interface and requires setup and
hold timing requirements of −65 ps and 95 ps relative to the
input clock (see Figure 123). The AD9208 has several features
that aid users in meeting these requirements. First, the SYSREF
sample event can be defined as either a synchronous low to high
transition or synchronous high to low transition. Second, the
AD9208 allows the SYSREF signal to be sampled using either
the rising edge or falling edge of the input clock. Figure 123,
Figure 124, Figure 125, and Figure 126 show all four possible
combinations.
The third SYSREF related feature available is the ability to
ignore a programmable number (up to 16) of SYSREF events.
The AD9208 is able to ignore N SYSREF events (note that the
SYSREF ignore feature is enabled by setting the SYSREF mode
register (Register 0x0120, Bits[2:1]) to 2'b10, which is labeled as
N-shot mode. This feature is useful for handling periodic SYSREF
signals, which need time to settle after startup. Ignoring SYSREF
until the clocks in the system have settled can avoid an inaccurate
SYSREF trigger. Figure 127 shows an example of the SYSREF
ignore feature when ignoring three SYSREF events.
CLK
SYSREF
KEEP OUT WINDOW
SYSREF
SAMPLE POINT
HOLD
REQUIREMENT
95ps
SETUP
REQUIREMENT
–65ps
15547-118
Figure 123. SYSREF Setup and Hold Time Requirements—SYSREF Low to
High Transition Using Rising Edge Clock (Default)
CLK
S
YSREF
SYSREF
SAMPLE POINT
HOLD
REQUIREMENT
95ps
SETUP
REQUIREMENT
–65ps
15547-119
Figure 124. SYSREF Low to High Transition Using Falling Edge Clock Capture
(Register 0x0120, Bit 4 = 1’b0; Register 0x0120, Bit 3 = 1’b1)
CLK
SYSREF
SYSREF
SAMPLE POINT
HOLD
REQUIREMENT
95ps
SETUP
REQUIREMENT
–65ps
15547-120
Figure 125. SYSREF High to Low Transition Using Rising Edge Clock Capture
(Register 0x0120, Bit 4 = 1’b1; Register 0x0120, Bit 3 = 1’b0)
SYSREF
SAMPLE POINT
CLK
SYSREF
HOLD
REQUIREMENT
95ps
SETUP
REQUIREMENT
–65ps
15547-121
Figure 126. SYSREF High to Low Transition Using Falling Edge Clock Capture
(Register 0x0120, Bit 4 = 1’b1; Register 0x0120, Bit 3 = 1’b1)
Data Sheet AD9208
Rev. 0 | Page 83 of 136
CLK
SYSREF
SYSREF SAMPLE PART 1 SYSREF SAMPLE PART 2 SYSREF SAMPLE PART 3 SYSREF SAMPLE PART 4 SYSREF SAMPLE PART 5
IGNORE FIRST THREE SYSREFs SAMPLE THE FOURTH SYSREF
15547-122
Figure 127. SYSREF Ignore Example (SYSREF Ignore Count, Register 0x0121, Bits[3:0] = 3)
SAMPLE CLOCK
SYSREF
SYSREF SKEW WINDOW = ±1
SYSREF SKEW WINDOW = ±2
SYSREF SKEW WINDOW = ±3
SYSREF SKEW WINDOW = 0
15547-123
Figure 128. SYSREF Skew Window
When in continuous SYSREF mode (Register 0x0120, Bits[2:1] =
1), the AD9208 monitors the placement of the SYSREF leading
edge compared to the internal LMFC. If the SYSREF is captured
with a clock edge other than the one that is aligned with LMFC,
the AD9208 initiates a resynchronization of the link. Because
input clock rates for AD9208 can be up to 4 GHz, the AD9208
provides another SYSREF related feature that makes it possible
to accommodate periodic SYSREF signals where cycle accurate
capture is not feasible or not required. For these scenarios, the
AD9208 has a programmable SYSREF skew window that allows
the internal dividers to remain undisturbed unless SYSREF
occurs outside the skew window. The resolution of the SYSREF
skew window is set in sample clock cycles. If the SYSREF negative
skew window is 1 and the positive skew window is 1, the total
skew window is ±1 sample clock cycles, meaning that, as long as
SYSREF is captured within ±1 sample clock cycle of the clock that
is aligned with LMFC, the link continues to operate normally. If
the SYSREF has jitter, which can cause a misalignment between
SYSREF and LMFC, this feature allows the system to continue
running without a resynchronization, while still allowing the
device to monitor for larger errors not caused by jitter. For the
AD9208, the positive and negative skew window is controlled by
the SYSREF window negative register (Register 0x0122, Bits[3:2])
and SYSREF window positive register (Register 0x0122, Bits[1:0]).
Figure 128 shows information on the location of the skew window
settings relative to Phase 0 of the internal dividers. Negative skew
is defined as occurring before the internal dividers reach Phase 0,
and positive skew is defined after the internal dividers reach
Phase 0.
AD9208 Data Sheet
Rev. 0 | Page 84 of 136
SYSREF± SETUP/HOLD WINDOW MONITOR
To ensure a valid SYSREF signal capture, the AD9208 has a
SYSREF± setup/hold window monitor. This feature allows the
system designer to determine the location of the SYSREF± signals
relative to the CLK± signals by reading back the amount of
setup/hold margin on the interface through the memory map.
Figure 129 and Figure 130 show the setup and hold status values
for different phases of SYSREF±. The setup detector returns the
status of the SYSREF± signal before the CLK± edge, and the
hold detector returns the status of the SYSREF signal after the
CLK± edge. Register 0x0128 stores the status of SYSREF± and
notifies the user if the SYSREF± signal is captured by the ADC.
Table 36 shows the description of the contents of Register 0x0128
and how to interpret them.
VALID
REG 0x0128[3:0]
CLK±
INPUT
SYSREF±
INPUT
FLIP-FLOP
HOLD (MIN)
FLIP-FLOP
HOLD (MIN)
FLIP-FLOP
SETUP (MIN)
0xF
0xE
0xD
0xC
0xB
0xA
0x9
0x8
0x7
0x6
0x5
0x4
0x3
0x2
0x1
0x0
15547-124
Figure 129. SYSREF± Setup Detector
Data Sheet AD9208
Rev. 0 | Page 85 of 136
CLK±
INPUT
SYSREF±
INPUT VALID
REG 0x0128[7:4]
FLIP-FLOP
HOLD (MIN)
FLIP-FLOP
HOLD (MIN)
FLIP-FLOP
SETUP (MIN)
0x
F
0xE
0xD
0xC
0xB
0xA
0x9
0x8
0x7
0x6
0x5
0x4
0x3
0x2
0x1
0x0
15547-125
Figure 130. SYSREF± Hold Detector
Table 36. SYSREF± Setup/Hold Monitor, Register 0x0128
Register 0x0128, Bits[7:4]
Hold Status
Register 0x0128, Bits[3:0]
Setup Status Description
0x0 0x0 to 0x7 Possible setup error. The smaller this number, the smaller the setup margin.
0x0 to 0x8 0x8 No setup or hold error (best hold margin).
0x8 0x9 to 0xF No setup or hold error (best setup and hold margin).
0x8 0x0 No setup or hold error (best setup margin).
0x9 to 0xF 0x0 Possible hold error. The larger this number, the smaller the hold margin.
0x0 0x0 Possible setup or hold error.
AD9208 Data Sheet
Rev. 0 | Page 86 of 136
LATENCY
END TO END TOTAL LATENCY
Tot al l atenc y in t he AD9208 is dependent on the chip
application mode and the JESD204B configuration. For any
given combination of these parameters, the latency is
deterministic, however, the value of this deterministic latency
must be calculated as described in the Example Latency
Calculations section.
Table 34 shows the combined latency through the ADC and
DSP for the different chip application modes supported by the
AD9208. Table 35 shows the latency through the JESD204B
block for each application mode based on the M/L ratio. For
both tables, latency is typical and is in units of the encode clock.
The latency through the JESD204B block does not depend on
the output data type (real or complex). Therefore, data type is
not included in Table 35.
To determine the total latency, select the appropriate ADC + DSP
latency from Table 34 and add it to the appropriate JESD204B
latency from Table 35. Example calculations are provided in the
following section.
EXAMPLE LATENCY CALCULATIONS
Example Configuration 1 is as follows:
ADC application mode = full bandwidth
Real outputs
L = 8, M = 2, F = 1, S = 2 (JESD204B mode)
20 × (M/L) = 5
Latency = 31 + 44 = 75 encode clocks
Example Configuration 2 is as follows:
ADC application mode = DCM4
Complex outputs
L = 4, M = 2, F = 1, S = 1 (JESD204B mode)
20 × (M/L) = 10
Latency = 162 + 88 = 250 encode clocks
LMFC REFERENCED LATENCY
Some FPGA vendors may require the end user to know LMFC-
referenced latency to make appropriate deterministic latency
adjustments. If they are required, the latency values in Table 34
and Table 35 can be used for the analog in to LMFC and LMFC
to data out latency values.
Data Sheet AD9208
Rev. 0 | Page 87 of 136
Table 37. Latency Through the ADC + DSP Blocks (Number of Sample Clocks)1
Chip Application Mode Enabled Filters ADC + DSP Latency
Full Bandwidth Not applicable 31
DCM1 (Real) HB1 90
DCM2 (Complex) HB1 90
DCM3 (Complex) TB1 102
DCM2 (Real) HB2 + HB1 162
DCM4 (Complex) HB2 + HB1 162
DCM3 (Real) TB2 + HB1 212
DCM6 (Complex) TB2 + HB1 212
DCM4 (Real) HB3 +HB2 + HB1 292
DCM8 (Complex) HB3 +HB2 + HB1 292
DCM5 (Real) FB2 + HB1 380
DCM10 (Complex) FB2 + HB1 380
DCM6 (Real) TB2 + HB2 + HB1 424
DCM12 (Complex) TB2 + HB2 + HB1 424
DCM15 (Real) FB2 + TB1 500
DCM8 (Real) HB4 + HB3 + HB2 + HB1 552
DCM16 (Complex) HB4 + HB3 + HB2 + HB1 552
DCM10 (Real) FB2 + HB2 + HB1 694
DCM20 (Complex) FB2 + HB2 + HB1 694
DCM12 (Real) TB2 + HB3 + HB2 + HB1 814
DCM24 (Complex) TB2 + HB3 + HB2 + HB1 814
DCM30 (Complex) HB2 + FB2 + TB1 836
DCM20 (Real) FB2 + HB3 + HB2 + HB1 1420
DCM40 (Complex) FB2 + HB3 + HB2 + HB1 1420
DCM24 (Real) TB2 + HB4 + HB3 + HB2 + HB1 1594
DCM48 (Complex) TB2 + HB4 + HB3 + HB2 + HB1 1594
1 DCMx indicates the decimation ratio.
Table 38. Latency Through JESD204B Block (Number of Sample Clocks)1
Chip Application Mode
M/L Ratio2
0.125 0.25 0.5 1 2 4 8
Full Bandwidth 82 44 25 14 7 9 3
DCM1 82 44 25 14 7 N/A N/A
DCM2 160 84 46 27 14 7 N/A
DCM3 237 124 67 39 21 11 N/A
DCM4 315 164 88 50 27 14 9
DCM5 N/A 2033 1093 623 433 N/A N/A
DCM6 N/A 243 130 73 39 21 14
DCM8 N/A 323 172 96 50 27 18
DCM10 N/A N/A 213 119 62 33 22
DCM12 N/A N/A 255 142 73 39 27
DCM15 N/A N/A 3184 1764 904 474 334
DCM16 N/A N/A 3394 1884 964 504 354
DCM20 N/A N/A N/A 233 119 62 43
DCM24 N/A N/A N/A 279 142 73 51
DCM30 N/A N/A N/A 3484 1764 904 624
DCM40 N/A N/A N/A N/A 2334 1194 824
DCM48 N/A N/A N/A N/A 2794 1424 974
1 N/A means not applicable and indicates that the application mode is not supported at the M/L ratio listed.
2 M/L ratio is the number of converters divided by the number of lanes for the configuration.
3 The application mode at the M/L ratio listed is only supported in real output mode.
4 The application mode at the M/L ratio listed is only supported in complex output mode.
AD9208 Data Sheet
Rev. 0 | Page 88 of 136
TEST MODES
ADC TEST MODES
The AD9208 has various test options that aid in the system level
implementation. The AD9208 has ADC test modes that are
available in Register 0x550. These test modes are described in
Table 39. When an output test mode is enabled, the analog section
of the ADC is disconnected from the digital back-end blocks,
and the test pattern is run through the output formatting block.
Some of the test patterns are subject to output formatting, and
some are not. The PN generators from the PN sequence tests
can be reset by setting Bit 4 or Bit 5 of Register 0x0550. These
tests can be performed with or without an analog signal (if
present, the analog signal is ignored); however, they do require
an encode clock.
If the application mode is set to select a DDC mode of
operation, the test modes must be enabled for each DDC
enabled. The test patterns can be enabled via Bit 2 and Bit 0 of
Register 0x0327, Register 0x0347, and Register 0x0367,
depending on which DDC(s) are selected. The (I) data uses the
test patterns selected for Channel A, and the (Q) data uses the
test patterns selected for Channel B. For DDC3 only, the (I) data
uses the test patterns from Channel A, and the (Q) data does
not output test patterns. Bit 0 of Register 0x0387 selects the
Channel A test patterns to be used for the (I) data. For more
information, see the AN-877 Application Note, Interfacing to
High Speed ADCs via SPI.
Table 39. ADC Test Modes
Output Test Mode
Bit Sequence Pattern Name Expression
Default/
Seed Value Sample (N, N + 1, N + 2, …)
0000 Off (default) Not applicable Not applicable Not applicable
0001 Midscale short 0000 0000 0000 Not applicable Not applicable
0010 +Full-scale short 01 1111 1111 1111 Not applicable Not applicable
0011 −Full-scale short 10 0000 0000 0000 Not applicable Not applicable
0100 Checkerboard 10 1010 1010 1010 Not applicable 0x1555, 0x2AAA, 0x1555, 0x2AAA, 0x1555
0101 PN sequence long x23 + x18 + 1 0x3AFF 0x3FD7, 0x0002, 0x26E0, 0x0A3D, 0x1CA6
0110 PN sequence short x9 + x5 + 1 0x0092 0x125B, 0x3C9A, 0x2660, 0x0c65, 0x0697
0111 One-/zero-word toggle 11 1111 1111 1111 Not applicable 0x0000, 0x3FFF, 0x0000, 0x3FFF, 0x0000
1000 User input Register 0x0551 to
Register 0x0558
Not applicable User Pattern 1[15:2], User Pattern 2[15:2],
User Pattern 3[15:2], User Pattern 4[15:2],
User Pattern 1[15:2] … for repeat mode
User Pattern 1[15:2], User Pattern 2[15:2],
User Pattern 3[15:2], User Pattern 4[15:2],
0x0000 … for single mode
1111 Ramp output (x) % 214 Not applicable (x) % 214, (x +1) % 214, (x +2) % 214, (x +3) % 214
Data Sheet AD9208
Rev. 0 | Page 89 of 136
JESD204B BLOCK TEST MODES
In addition to the ADC pipeline test modes, the AD9208 also has
flexible test modes in the JESD204B block. These test modes are
listed in Register 0x0573 and Register 0x0574. These test patterns
can be injected at various points along the output datapath. These
test injection points are shown in Figure 107. Table 40 describes
the various test modes available in the JESD204B block. For the
AD9208, a transition from test modes (Register 0x0573 ≠ 0x00)
to normal mode (Register 0x0573 = 0x00) requires an SPI soft
reset. This is done by writing 0x81 to Register 0x0000 (self cleared).
Transport Layer Sample Test Mode
The transport layer samples are implemented in the AD9208 as
defined by Section 5.1.6.3 in the JEDEC JESD204B specification.
These tests are shown in Register 0x0571, Bit 5. The test pattern
is equivalent to the raw samples from the ADC.
Interface Test Modes
The interface test modes are described in Register 0x0573, Bits[3:0].
These test modes are also explained in Table 40. The interface tests
can be injected at various points along the data. See Figure 107
for more information on the test injection points. Register 0x0573,
Bits[5:4] show where these tests are injected.
Table 41, Table 42, and Table 43 show examples of some of the
test modes when injected at the JESD204B sample input, PHY
10-bit input, and scrambler 8-bit input. UPx in the tables
represent the user pattern control bits from the user register
map.
Table 40. JESD204B Interface Test Modes
Output Test Mode
Bit Sequence Pattern Name Expression Default
0000 Off (default) Not applicable Not applicable
0001 Alternating checker board 0x5555, 0xAAAA, 0x5555, … Not applicable
0010 1/0 word toggle 0x0000, 0xFFFF, 0x0000, … Not applicable
0011 31-bit PN sequence x31 + x28 + 1 0x0003AFFF
0100 23-bit PN sequence x23 + x18 + 1 0x003AFF
0101 15-bit PN sequence x15 + x14 + 1 0x03AF
0110 9-bit PN sequence x9 + x5 + 1 0x092
0111 7-bit PN sequence x7 + x6 + 1 0x07
1000 Ramp output (x) % 216 Ramp size depends on test injection point
1110 Continuous/repeat user test Register 0x0551 to Register 0x0558 User Pattern 1 to User Pattern 4, then repeat
1111 Single user test Register 0x0551 to Register 0x0558 User Pattern 1 to User Pattern 4, then zeros
Table 41. JESD204B Sample Input for M = 2, S = 2, N' = 16 (Register 0x0573, Bits[5:4] = 'b00)
Frame
Number
Converter
Number
Sample
Number
Alternating
Checkerboard
1/0 Word
Toggle Ramp PN9 PN23 User Repeat User Single
0 0 0 0x5555 0x0000 (x) % 216 0x496F 0xFF5C UP1[15:0] UP1[15:0]
0 0 1 0x5555 0x0000 (x) % 216 0x496F 0xFF5C UP1[15:0] UP1[15:0]
0 1 0 0x5555 0x0000 (x) % 216 0x496F 0xFF5C UP1[15:0] UP1[15:0]
0 1 1 0x5555 0x0000 (x) % 216 0x496F 0xFF5C UP1[15:0] UP1[15:0]
1 0 0 0xAAAA 0xFFFF (x +1) % 216 0xC9A9 0x0029 UP2[15:0] UP2[15:0]
1 0 1 0xAAAA 0xFFFF (x +1) % 216 0xC9A9 0x0029 UP2[15:0] UP2[15:0]
1 1 0 0xAAAA 0xFFFF (x +1) % 216 0xC9A9 0x0029 UP2[15:0] UP2[15:0]
1 1 1 0xAAAA 0xFFFF (x +1) % 216 0xC9A9 0x0029 UP2[15:0] UP2[15:0]
2 0 0 0x5555 0x0000 (x +2) % 216 0x980C 0xB80A UP3[15:0] UP3[15:0]
2 0 1 0x5555 0x0000 (x +2) % 216 0x980C 0xB80A UP3[15:0] UP3[15:0]
2 1 0 0x5555 0x0000 (x +2) % 216 0x980C 0xB80A UP3[15:0] UP3[15:0]
2 1 1 0x5555 0x0000 (x +2) % 216 0x980C 0xB80A UP3[15:0] UP3[15:0]
3 0 0 0xAAAA 0xFFFF (x +3) % 216 0x651A 0x3D72 UP4[15:0] UP4[15:0]
3 0 1 0xAAAA 0xFFFF (x +3) % 216 0x651A 0x3D72 UP4[15:0] UP4[15:0]
3 1 0 0xAAAA 0xFFFF (x +3) % 216 0x651A 0x3D72 UP4[15:0] UP4[15:0]
3 1 1 0xAAAA 0xFFFF (x +3) % 216 0x651A 0x3D72 UP4[15:0] UP4[15:0]
4 0 0 0x5555 0x0000 (x +4) % 216 0x5FD1 0x9B26 UP1[15:0] 0x0000
4 0 1 0x5555 0x0000 (x +4) % 216 0x5FD1 0x9B26 UP1[15:0] 0x0000
4 1 0 0x5555 0x0000 (x +4) % 216 0x5FD1 0x9B26 UP1[15:0] 0x0000
4 1 1 0x5555 0x0000 (x +4) % 216 0x5FD1 0x9B26 UP1[15:0] 0x0000
AD9208 Data Sheet
Rev. 0 | Page 90 of 136
Table 42. Physical Layer 10-Bit Input (Register 0x0573, Bits[5:4] = 'b01)
10-Bit Symbol
Number
Alternating
Checkerboard
1/0 Word
Toggle Ramp PN9 PN23 User Repeat User Single
0 0x155 0x000 (x) % 210 0x125 0x3FD UP1[15:6] UP1[15:6]
1 0x2AA 0x3FF (x + 1) % 210 0x2FC 0x1C0 UP2[15:6] UP2[15:6]
2 0x155 0x000 (x + 2) % 210 0x26A 0x00A UP3[15:6] UP3[15:6]
3 0x2AA 0x3FF (x + 3) % 210 0x198 0x1B8 UP4[15:6] UP4[15:6]
4 0x155 0x000 (x + 4) % 210 0x031 0x028 UP1[15:6] 0x000
5 0x2AA 0x3FF (x + 5) % 210 0x251 0x3D7 UP2[15:6] 0x000
6 0x155 0x000 (x + 6) % 210 0x297 0x0A6 UP3[15:6] 0x000
7 0x2AA 0x3FF (x + 7) % 210 0x3D1 0x326 UP4[15:6] 0x000
8 0x155 0x000 (x + 8) % 210 0x18E 0x10F UP1[15:6] 0x000
9 0x2AA 0x3FF (x + 9) % 210 0x2CB 0x3FD UP2[15:6] 0x000
10 0x155 0x000 (x + 10) % 210 0x0F1 0x31E UP3[15:6] 0x000
11 0x2AA 0x3FF (x + 11) % 210 0x3DD 0x008 UP4[15:6] 0x000
Table 43. Scrambler 8-bit Input (Register 0x0573, Bits[5:4] = 'b10)
8-Bit Octet
Number
Alternating
Checkerboard
1/0 Word
Toggle Ramp PN9 PN23 User Repeat User Single
0 0x55 0x00 (x) % 28 0x49 0xFF UP1[15:9] UP1[15:9]
1 0xAA 0xFF (x + 1) % 28 0x6F 0x5C UP2[15:9] UP2[15:9]
2 0x55 0x00 (x + 2) % 28 0xC9 0x00 UP3[15:9] UP3[15:9]
3 0xAA 0xFF (x + 3) % 28 0xA9 0x29 UP4[15:9] UP4[15:9]
4 0x55 0x00 (x + 4) % 28 0x98 0xB8 UP1[15:9] 0x00
5 0xAA 0xFF (x + 5) % 28 0x0C 0x0A UP2[15:9] 0x00
6 0x55 0x00 (x + 6) % 28 0x65 0x3D UP3[15:9] 0x00
7 0xAA 0xFF (x + 7) % 28 0x1A 0x72 UP4[15:9] 0x00
8 0x55 0x00 (x + 8) % 28 0x5F 0x9B UP1[15:9] 0x00
9 0xAA 0xFF (x + 9) % 28 0xD1 0x26 UP2[15:9] 0x00
10 0x55 0x00 (x + 10) % 28 0x63 0x43 UP3[15:9] 0x00
11 0xAA 0xFF (x + 11) % 28 0xAC 0xFF UP4[15:9] 0x00
Data Link Layer Test Modes
The data link layer test modes are implemented in the AD9208
as defined by Section 5.3.3.8.2 in the JEDEC JESD204B
Specification. These tests are shown in Register 0x0574,
Bits[2:0]. Test patterns inserted at this point are useful for
verifying the functionality of the data link layer. When the data
link layer test modes are enabled, disable SYNCINB± by writing
0xC0 to Register 0x0572.
Data Sheet AD9208
Rev. 0 | Page 91 of 136
SERIAL PORT INTERFACE
The AD9208 SPI allows the user to configure the converter for
specific functions or operations through a structured register
space provided inside the ADC. The SPI gives the user added
flexibility and customization, depending on the application.
Addresses are accessed via the serial port and can be written to
or read from via the port. Memory is organized into bytes that
can be further divided into fields. These fields are documented
in the Memory Map section. For detailed operational information,
see the Serial Control Interface Standard (Rev. 1.0).
CONFIGURATION USING THE SPI
Three pins define the SPI of the AD9208 ADC: the SCLK pin,
the SDIO pin, and the CSB pin (see Table 44). The SCLK (serial
clock) pin synchronizes the read and write data presented
from/to the ADC. The SDIO (serial data input/output) pin is a
dual-purpose pin that allows data to be sent and read from the
internal ADC memory map registers. The CSB (chip select bar)
pin is an active low control that enables or disables the read and
write cycles.
Table 44. SPI Pins
Pin Function
SCLK Serial clock. The serial shift clock input that is used to
synchronize serial interface, reads, and writes.
SDIO Serial data input/output. A dual-purpose pin that
typically serves as an input or an output, depending on
the instruction being sent and the relative position in the
timing frame.
CSB Chip select bar. An active low control that gates the read
and write cycles.
The falling edge of CSB, in conjunction with the rising edge of
SCLK, determines the start of the framing. An example of the
serial timing and its definitions can be found in Figure 4 and
Table 5.
Other modes involving the CSB pin are available. The CSB pin
can be held low indefinitely, which permanently enables the
device; this is called streaming. The CSB can stall high between
bytes to allow additional external timing. When CSB is tied
high, SPI functions are placed in a high impedance mode. This
mode turns on any SPI pin secondary functions.
All data is composed of 8-bit words. The first bit of each
individual byte of serial data indicates whether a read or write
command is issued, which allows the SDIO pin to change
direction from an input to an output.
In addition to word length, the instruction phase determines
whether the serial frame is a read or write operation, allowing
the serial port to be used both to program the chip and to read
the contents of the on-chip memory. If the instruction is a
readback operation, performing a readback causes the SDIO pin
to change direction from an input to an output at the appropriate
point in the serial frame.
Data can be sent in MSB first mode or in LSB first mode. MSB
first is the default on power-up and can be changed via the SPI
port configuration register. For more information about this
and other features, see the Serial Control Interface Standard
(Rev. 1.0).
HARDWARE INTERFACE
The pins described in Table 44 comprise the physical interface
between the user programming device and the serial port of the
AD9208. The SCLK pin and the CSB pin function as inputs
when using the SPI interface. The SDIO pin is bidirectional,
functioning as an input during write phases and as an output
during readback.
The SPI interface is flexible enough to be controlled by either
FPGAs or microcontrollers. One method for SPI configuration
is described in detail in the AN-812 Application Note,
Microcontroller-Based Serial Port Interface (SPI) Boot Circuit.
Do not activate the SPI port during periods when the full
dynamic performance of the converter is required. Because the
SCLK signal, the CSB signal, and the SDIO signal are typically
asynchronous to the ADC clock, noise from these signals can
degrade converter performance. If the on-board SPI bus is
used for other devices, it may be necessary to provide buffers
between this bus and the AD9208 to prevent these signals from
transitioning at the converter inputs during critical sampling
periods.
SPI ACCESSIBLE FEATURES
Table 45 provides a brief description of the general features that
are accessible via the SPI. These features are described in detail
in the Serial Control Interface Standard (Rev. 1.0). The AD9208
device specific features are described in the Memory Map section.
Table 45. Features Accessible Using the SPI
Feature Description
Mode Allows the user to set either power-down mode or standby mode.
Clock Allows the user to access the clock divider via the SPI.
DDC Allows the user to set up decimation filters for different applications.
Test Input/Output Allows the user to set test modes to have known data on output bits.
Output Mode Allows the user to set up outputs.
SERDES Output Setup Allows the user to vary SERDES settings such as swing and emphasis.
AD9208 Data Sheet
Rev. 0 | Page 92 of 136
MEMORY MAP
READING THE MEMORY MAP REGISTER TABLE
Each row in the memory map register table has eight bit
locations. The memory map is divided into the following
sections:
Analog Devices SPI registers (Register 0x0000 to
Register 0x000F)
Clock/SYSREF/chip power-down pin control registers
(Register 0x003F to Register 0x0201)
Fast detect and signal monitor control registers
(Register 0x0245 to Register 0x027A)
DDC function registers (Register 0x0300 to
Register 0x03CD)
Digital outputs and test modes registers (Register 0x0550 to
Register 0x05CB)
Programmable filter control and coefficients registers
(Register 0x0DF8 to Register 0x0F7F)
VREF/analog input control registers (Register 0x18A6 to
Register 0x1A4D)
Table 43 (see the Memory Map Register Details section)
documents the default hexadecimal value for each hexadecimal
address shown. The column with the heading Bit 7 (MSB) is the
start of the default hexadecimal value given. For example,
Address 0x0561, the output sample mode register, has a
hexadecimal default value of 0x01, which means that Bit 0 = 1,
and the remaining bits are 0s. This setting is the default output
format value, which is twos complement. For more information
on this function and others, see Table 43.
Open and Reserved Locations
All address and bit locations that are not included in Table 43
are not currently supported for this device. Write unused bits
of a valid address location with 0s unless the default value is
set otherwise. Writing to these locations is required only when
part of an address location is unassigned (for example,
Address 0x0561). If the entire address location is open (for
example, Address 0x0013), do not write to this address location.
Default Values
After the AD9208 is reset, critical registers are loaded with
default values. The default values for the registers are given in
the memory map register table, Table 43.
Logic Levels
An explanation of logic level terminology follows:
“Bit is set” is synonymous with “bit is set to Logic 1” or
“writing Logic 1 for the bit.”
“Clear a bit” is synonymous with “bit is set to Logic 0” or
“writing Logic 0 for the bit.”
X denotes a don’t care bit.
Channel Specific Registers
Some channel setup functions, such as the buffer control
register (Register 0x1A4C), can be programmed to a different
value for each channel. In these cases, channel address locations
are internally duplicated for each channel. These registers and
bits are designated in Table 43 as local. These local registers and
bits can be accessed by setting the appropriate Channel A or
Channel B bits in Register 0x0008. If both bits are set, the
subsequent write affects the registers of both channels. In a read
cycle, set only Channel A or Channel B to read one of the two
registers. If both bits are set during an SPI read cycle, the device
returns the value for Channel A. Registers and bits designated as
global in Table 43 affect the entire device and the channel
features for which independent settings are not allowed
between channels. The settings in Register 0x0005 do not affect
the global registers and bits.
SPI Soft Reset
After issuing a soft reset by programming 0x81 to Register 0x0000,
the AD9208 requires 5 ms to recover. When programming the
AD9208 for application setup, ensure that an adequate delay is
programmed into the firmware after asserting the soft reset and
before starting the device setup.
Data Sheet AD9208
Rev. 0 | Page 93 of 136
MEMORY MAP REGISTER DETAILS
All address locations that are not included in Table 46 are not currently supported for this device and must not be written.
Table 46. Memory Map Register Details
Addr. Name Bits Bit Name Settings Description Reset Access
Analog Devices SPI Registers
0x0000 SPI Configuration A 7 Soft reset mirror
(self clearing)
Whenever a soft reset is issued, the user must wait 5 ms before
writing to any other register. This provides sufficient time for
the boot loader to complete.
0x0 R/WC
0 Do nothing.
1 Reset the SPI and registers (self clearing).
6 LSB first mirror 0x0 R/W
1 Least significant bit (LSB) shifted first for all SPI operations.
0 Most significant bit (MSB) shifted first for all SPI operations.
5 Address ascension mirror 0x0 R/W
0 Multibyte SPI operations cause addresses to autodecrement.
1 Multibyte SPI operations cause addresses to autoincrement.
[4:3] Reserved Reserved. 0x0 R
2 Address ascension 0x0 R/W
0 Multibyte SPI operations cause addresses to auto-decrement.
1 Multibyte SPI operations cause addresses to auto-increment.
1 LSB first 0x0 R/W
1 LSB shifted first for all SPI operations.
0 MSB shifted first for all SPI operations.
0 Soft reset (self clearing) Whenever a soft reset is issued, the user must wait 5 ms before
writing to any other register. This provides sufficient time for
the boot loader to complete.
0x0 R/WC
0 Do nothing.
1 Reset the SPI and registers (self clearing).
0x0001 SPI Configuration B [7:2] Reserved Reserved. 0x0 R
1 Datapath soft reset
(self clearing)
0x0 R/WC
0 Normal operation.
1 Datapath soft reset (self clearing).
0 Reserved Reserved. 0x0 R
0x0002 Chip configuration
(local)
[7:2] Reserved Reserved. 0x0 R
[1:0] Channel power mode Channel power modes. 0x0 R/W
00 Normal mode (power-up).
10 Standby mode; digital datapath clocks disabled; JESD204B
interface enabled.
11 Power-down mode; digital datapath clocks disabled; digital
datapath held in reset; JESD204B interface disabled.
0x0003 Chip type [7:0] Chip type Chip type. 0x03 R
0x3 High speed ADC.
0x0004 Chip ID LSB [7:0] Chip ID LSB [7:0] Chip ID. 0xE2 R
0xDF AD9208.
0x0005 Chip ID MSB [7:0] Chip ID MSB [15:8] Chip ID. 0x0 R
0x0006 Chip grade [7:4] Chip speed grade 0x0 Chip speed grade. 0x0 R
[3:0] Reserved Reserved. 0x0 R
0x0008 Device index [7:2] Reserved Reserved. 0x0 R
1 Channel B 0x1 R/W
0 ADC Core B does not receive the next SPI command.
1 ADC Core B receives the next SPI command.
0 Channel A 0x1 R/W
0 ADC Core A does not receive the next SPI command.
1 ADC Core A receives the next SPI command.
0x000A Scratch pad [7:0] Scratch pad Chip scratch pad register. This register provides a consistent
memory location for software debugging.
0x0 R/W
0x000B SPI revision [7:0] SPI revision SPI revision register. 0x01: Revision 1.0. 0x1 R
00000001 Revision 1.0.
AD9208 Data Sheet
Rev. 0 | Page 94 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x000C Vendor ID LSB [7:0] Vendor ID LSB Vendor ID [7:0]. 0x56 R
0x000D Vendor ID MSB [7:0] Vendor ID MSB Vendor ID [15:8]. 0x04 R
0x000F Transfer [7:1] Reserved Reserved. 0x0 R
0 Chip transfer Self clearing chip transfer bit. This bit is used to update the
DDC phase increment and phase offset registers when DDC
phase update mode (Register 0x0300, Bit 7 ) = 1. This makes it
possible to synchronously update the DDC mixer frequencies.
This bit is also used to update the coefficients for the
programmable filter (PFILT).
0x0 R/W
0 Do nothing. Bit is only cleared after transfer is complete.
1 Self clearing bit used to synchronize the transfer of data from
master to slave registers.
Clock/SYSREF/Chip PDWN Pin Control Registers
0x003F Chip PDWN pin
(local)
7 Local chip PDWN pin
disable
Function is determined by Register 0x0040, Bits[7:6]. 0x0 R/W
0 Power-down pin (PDWN/STBY) enabled (default).
1 Power-down pin (PDWN/STBY) disabled/ignored.
[6:0] Reserved Reserved. 0x0 R
0x0040 Chip Pin Control 1 [7:6] Global chip PDWN pin
functionality
External power-down pin functionality. Assertion of the
external power-down pin (PDWN/STBY) has higher priority
than the channel power mode control bits (Register 0x0002,
Bits[1:0]). The PDWN/STBY pin is only used when Register 0x0040,
Bits[7:6] = 00 or 01.
0x0 R/W
00 Power-down pin (default). Assertion of external power-down pin
(PDWN/STBY) causes the chip to enter full power-down mode.
01 Standby pin. Assertion of external power-down pin (PDWN/STBY)
causes the chip to enter standby mode.
10 Pin disabled. Power-down pin (PDWN/STBY) is ignored.
[5:3] Chip FD_B/GPIO_B0 pin
functionality
Fast Detect B/GPIO B0 pin functionality. 0x7 R/W
000 Fast Detect B output.
001 JESD204B LMFC output.
110 Pin functionality determined by 0x0041[7:4]
111 Disabled. Configured as input with weak pull-down (default).
[2:0] Chip FD_A/GPIO_A0 pin
functionality
Fast Detect A/GPIO A0 pin functionality. 0x7 R/W
000 Fast Detect A output.
001 JESD204B LMFC output.
110 Pin functionality determined by Register 0x0041, Bits[3:0]
111 Disabled. Configured as an input with weak pull-down (default).
0x0041 Chip Pin Control 2 [7:4] Chip FD_B/GPIO_B0 pin
secondary functionality
Fast Detect B/GPIO B0 pin secondary functionality (only used
when Register 0x0040, Bits[5:3] = 110).
0x0 R/W
0000 Chip GPIO B0 input (NCO channel selection).
0001 Chip transfer input.
1000 Master next trigger output (MNTO).
1001 Slave next trigger input (SNTI).
[3:0] Chip FD_A/GPIO_A0 pin
secondary functionality
Fast Detect A/GPIO B0 pin secondary functionality (only used
when Register 0x0040, Bits[2:0] = 110).
0x0 R/W
0000 Chip GPIO A0 input (NCO channel selection).
0001 Chip transfer input.
1000 Master next trigger output (MNTO).
1001 Slave next trigger input (SNTI).
Data Sheet AD9208
Rev. 0 | Page 95 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0042 Chip Pin Control 3 [7:4] Chip GPIO_B1 pin
functionality
GPIO B1 pin functionality. 0xF R/W
0000 Chip GPIO B1 input (NCO channel selection).
1000 Master next trigger output (MNTO).
1001 Slave next trigger input (SNTI).
1111 Disabled (configured as input with weak pull-down).
[3:0] Chip GPIO_B1 pin
functionality
GPIO A1 pin functionality. 0xF R/W
0000 Chip GPIO A1 input (NCO channel selection).
1000 Master next trigger output (MNTO).
1001 Slave next trigger input (SNTI).
1111 Disabled (configured as input with weak pull-down).
0x0108 Clock divider control [7:3] Reserved Reserved. 0x0 R
[2:0] Input clock divider
(CLK± pins)
0x0 R/W
00 Divide by 1.
01 Divide by 2.
11 Divide by 4.
0x0109 Clock divider
phase (local)
[7:4] Reserved Reserved. 0x0 R
[3:0] Clock divider phase offset 0x0 R/W
0000 0 input clock cycles delayed.
0001 ½ input clock cycles delayed (invert clock).
0010 1 input clock cycles delayed.
… …
1110 7 input clock cycles delayed.
1111 7½ input clock cycles delayed.
0x010A Clock divider and
SYSREF control
7 Clock divider auto phase
adjust enable
Clock divider autophase adjust enable. When enabled,
Register 0x0129, Bits[3:0] contain the phase of the divider when
SYSREF occurred. The actual divider phase offset =
Register 0x0129, Bits[3:0] + Register 0x0109, Bits[3:0].
0x0 R/W
0 Clock divider phase is not changed by SYSREF (disabled).
1 Clock divider phase is automatically adjusted by SYSREF (enabled).
[6:4] Reserved Reserved. 0x0 R
[3:2] Clock divider negative
skew window
Clock divider negative skew window (measured in ½ input
device clocks). Number of ½ clock cycles before the input
device clock by which captured SYSREF transitions are ignored.
Only used when Register 0x010A, Bit 7 = 1. Register 0x010A,
Bits[3:2] + Register 0x010A, Bits[1:0] < Register 0x0108, Bits[2:0].
This allows some uncertainty in the sampling of SYSREF
without disturbing the input clock divider. Also, SYSREF must
be disabled (Register 0x0120, Bits[2:1] = 0x0) when changing
this control field.
0x0 R/W
0 No negative skew; SYSREF must be captured accurately.
1 ½ device clock of negative skew.
10 1 device clocks of negative skew.
11 1½ device clocks of negative skew.
[1:0] Clock divider positive
skew window
Clock divider positive skew window (measured in ½ input
device clocks). Number of clock cycles after the input device
clock by which captured SYSREF transitions are ignored. Only
used when Register 0x010A, Bit 7 = 1. Register 0x010A, Bits[3:2] +
Register 0x010A, Bits[1:0] < Register 0x0108, Bits[2:0]. This
allows some uncertainty in the sampling of SYSREF without
disturbing the input clock divider. Also, SYSREF must be
disabled (Register 0x0120, Bits[2:1] = 0x0) when changing this
control field.
0x0 R/W
0 No positive skew; SYSREF must be captured accurately.
1 ½ device clock of positive skew.
10 1 device clocks of positive skew.
11 1½ device clocks of positive skew.
AD9208 Data Sheet
Rev. 0 | Page 96 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x010B Clock divider
SYSREF status
[7:4] Reserved Reserved. 0x0 R
[3:0] Clock divider SYSREF
offset
Clock divider phase status (measured in ½ clock cycles).
Internal clock divider phase of the captured SYSREF signal
applied to the phase offset. Only used when 0x010A[7] = 1.
When Register 0x010A, Bit 7 = 1, Register 0x010A, Bits[3:2] = 0,
and Register 0x010A, Bits[1:0] = 0, the clock divider SYSREF
offset = Register 0x0129, Bits[3:0].
0x0 R
0x0110 Clock delay control [7:3] Reserved Reserved. 0x0 R
[2:0] Clock delay mode select Clock delay mode select. Used in conjunction with
Register 0x0111 and Register 0x0112.
0x0 R/W
000 No clock delay.
010 Fine delay: only 0 to 16 delay steps are valid.
011 Fine delay (lowest jitter): only 0 to 16 delay steps are valid.
100 Fine delay: all 192 delay steps are valid.
110 Fine delay enabled (all 192 delay steps are valid); superfine
delay enabled (all 128 delay steps are valid).
0x0111 Clock superfine
delay (local)
[7:0] Clock superfine delay
adjust
Clock superfine delay adjust. This is an unsigned control to
adjust the superfine sample clock delay in 0.25 ps steps. These
bits are only used when Register 0x0110, Bits[2:0] = 010 or 110.
0x0 R/W
0x00 0 delay steps.
… …
0x08 8 delay steps.
… …
0x80 128 delay steps.
0x0112 Clock fine delay
(local)
[7:0] Set clock fine delay Clock fine delay adjust. This is an unsigned control to adjust the
fine sample clock skew in 1.725 ps steps. These bits are only
used when Register 0x0110, Bits[2:0] = 0x2, 0x3, 0x4, or 0x6.
Minimum = 0. Maximum = 192. Increment = 1. Unit = delay
steps.
0xC0 R/W
0x00 0 delay steps.
… …
0x08 8 delay steps.
… …
0xC0 192 delay steps.
0x011B Clock status [7:1] Reserved Reserved. 0x0 R
0 Input clock detect Clock detection status. 0x0 R
0 Input clock not detected.
1 Input clock detected/locked.
0x011C Clock Duty Cycle
Stabilizer 1 control
(local)
[7:2] Reserved Reserved 0x0 R/W
1 DCS1 enable Clock DCS1 enable. 0x1 R/W
0 DCS1 bypassed.
1 DCS1 enabled.
0 DCS1 power up Clock DCS1 power-up. 0x1 R/W
0 DCS1 powered down.
1 DCS1 powered up.
0x011E Clock Duty Cycle
Stabilizer 2 control
[7:2] Reserved Reserved. 0x0 R/W
1 DCS2 enable Clock DCS2 enable. 0x1 R/W
0 DCS2 bypassed.
1 DCS2 enabled.
0 DCS2 power up Clock DCS2 power-up. 0x1 R/W
0 DCS2 powered down.
1 DCS2 powered up.
Data Sheet AD9208
Rev. 0 | Page 97 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0120 SYSREF Control 1 7 Reserved Reserved. 0x0 R
6 SYSREF± flag reset 0x0 R/W
0 Normal flag operation.
1 SYSREF flags held in reset (setup and hold error flags cleared).
5 Reserved Reserved. 0x0 R
4 SYSREF± transition select 0x0 R/W
0 SYSREF is valid on low to high transitions using the selected
CLK± edge. When changing this setting, SYSREF± mode select
must be set to disabled.
1 SYSREF is valid on high to low transitions using the selected
CLK± edge. When changing this setting, SYSREF± mode select
must be set to disabled.
3 CLK± edge select 0x0 R/W
0 Captured on the rising edge of CLK± input.
1 Captured on the falling edge of CLK± input.
[2:1] SYSREF± mode select 0x0 R/W
0 Disabled.
1 Continuous.
10 N-shot.
0 Reserved Reserved. 0x0 R
0x0121 SYSREF Control 2 [7:4] Reserved Reserved. 0x0 R
[3:0] SYSREF N-shot ignore
counter select
0x0 R/W
0000 Next SYSREF only (do not ignore).
0001 Ignore the first SYSREF± transition.
0010 Ignore the first two SYSREF± transitions.
0011 Ignore the first three SYSREF± transitions.
… …
1110 Ignore the first 14 SYSREF± transitions.
1111 Ignore the first 15 SYSREF± transitions.
0x0122 SYSREF Control 3 [7:4] Reserved Reserved. 0x0 R
[3:2] SYSREF window negative Negative skew window (measured in sample clocks). Number
of clock cycles before the sample clock by which captured
SYSREF transitions are ignored.
0x0 R/W
00 No negative skew; SYSREF must be captured accurately.
01 One sample clock of negative skew.
10 Two sample clocks of negative skew.
11 Three sample clocks of negative skew.
[1:0] SYSREF window positive Positive skew window (measured in sample clocks). Number of
clock cycles before the sample clock by which captured SYSREF
transitions are ignored.
0x0 R/W
00 No positive skew; SYSREF must be captured accurately.
01 One sample clock of positive skew.
10 Two sample clocks of positive skew.
11 Three sample clocks of positive skew.
0x0123 SYSREF Control 4 7 Reserved Reserved. 0x0 R
[6:0] SYSREF± timestamp
delay, Bits[6:0]
SYSREF timestamp delay (in converter sample clock cycles). 0x00 R/W
0 0 sample clock cycle delay.
1 1 sample clock cycle delay.
… …
111 1111 127 sample clock cycle delay.
0x0128 SYSREF Status 1 [7:4] SYSREF± hold status SYSREF hold status. 0x0 R
[3:0] SYSREF± setup status SYSREF setup status. 0x0 R
AD9208 Data Sheet
Rev. 0 | Page 98 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0129 SYSREF Status 2 [7:4] Reserved Reserved. 0x0 R
[3:0] Clock divider phase when
SYSREF± was captured
SYSREF divider phase. Represents the phase of the divider
when SYSREF was captured.
0x0 R
0000 In phase.
0001 SYSREF± is ½ cycle delayed from clock.
0010 SYSREF± is 1 cycle delayed from clock.
0011 SYSREF± is 1½ input clock cycles delayed.
0100 SYSREF± is 2 input clock cycles delayed.
… …
1111 SYSREF± is 7½ input clock cycles delayed.
0x012A SYSREF Status 3 [7:0] SYSREF counter, Bits[7:0]
increments when a
SYSREF± is captured
SYSREF count. Running counter that increments whenever a
SYSREF event is captured. Reset by Register 0x120, Bit 6. Wraps
around at 255. Read these bits only when Register 0x120, Bits[2:1]
are set to disabled.
0x0 R
0x01FF Chip sync mode [7:1] Reserved Reserved. 0x0 R
0 Synchronization mode 0x0 R/W
0 JESD204B synchronization mode. The SYSREF signal resets all
internal clock dividers. Use this mode when synchronizing
multiple chips as specified in the JESD204B standard. If the
phase of any of the dividers must change, the JESD204B link
goes down.
1 Timestamp mode. The SYSREF signal does not reset internal
clock dividers. In this mode, the JESD204B link and the signal
monitor are not affected by the SYSREF signal. The SYSREF
signal timestamps a sample as it passes through the ADC and is
used as a control bit in the JESD204B output word.
Chip Operating Mode Control Registers
0x0200 Chip mode [7:6] Reserved Reserved. 0x0 R/W
5 Chip Q ignore Chip real (I) only selection. 0x0 R/W
0 Both real (I) and complex (Q) selected.
1 Only real (I) selected; complex (Q) is ignored.
4 Reserved Reserved. 0x0 R
[3:0] Chip application mode 0x0 R/W
0000 Full bandwidth mode (default).
0001 One DDC mode (DDC0 only)
0010 Two DDC mode (DDC0 and DDC1 only)
0011 Four DDC mode (DDC0, DDC1, DDC2, and DDC3)
0x0201 Chip decimation
ratio
[7:4] Reserved Reserved. 0x0 R
[3:0] Chip decimation ratio Chip decimation ratio. 0x0 R/W
0000 Full sample rate (decimate by 1, DDCs are bypassed).
0001 Decimate by 2.
1000 Decimate by 3.
0010 Decimate by 4.
0101 Decimate by 5.
1001 Decimate by 6.
0011 Decimate by 8.
0110 Decimate by 10.
1010 Decimate by 12.
0111 Decimate by 15.
0100 Decimate by 16.
1101 Decimate by 20.
1011 Decimate by 24.
1110 Decimate by 30.
1111 Decimate by 40.
1100 Decimate by 48.
Data Sheet AD9208
Rev. 0 | Page 99 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
Fast Detect and Signal Monitor Control Registers
0x0245 Fast detect control
(local)
[7:4] Reserved Reserved. 0x0 R
3 Force FD_A/FD_B pins 0x0 R/W
0 Normal operation of the fast detect pin.
1 Force a value on the fast detect pin (see Bit 2).
2 Force value of
FD_A/FD_B pins
The fast detect output pin for this channel is set to this value
when the output is forced.
0x0 R/W
1 Reserved Reserved. 0x0 R
0 Enable fast detect output 0x0 R/W
0 Fast detect disabled.
1 Fast detect enabled.
0x0247 Fast detect up LSB
(local)
[7:0] Fast detect upper
threshold
LSBs of the fast detect upper threshold. This register contains
the 8 LSBs of the programmable 13-bit upper threshold that is
compared to the fine ADC magnitude.
0x0 R/W
0x0248 Fast detect up MSB
(local)
[7:5] Reserved Reserved. 0x0 R
[4:0] Fast detect upper
threshold
MSBs of the fast detect upper threshold. This register contains
the 8 LSBS of the programmable 13-bit upper threshold that is
compared to the fine ADC magnitude.
0x0 R/W
0x0249 Fast detect low LSB
(local)
[7:0] Fast detect lower
threshold
LSBs of the fast detect lower threshold. This register contains
the 8 LSBS of the programmable 13-bit lower threshold that is
compared to the fine ADC magnitude.
0x0 R/W
0x024A Fast detect low
MSB (local)
[7:5] Reserved Reserved. 0x0 R
[4:0] Fast detect lower
threshold
MSBs of the fast detect lower threshold. This register contains
the 8 LSBs of the programmable 13-bit lower threshold that is
compared to the fine ADC magnitude
0x0 R/W
0x024B Fast detect dwell
LSB (local)
[7:0] Fast detect dwell time LSBs of the fast detect dwell time counter target. This is a load
value for a 16-bit counter that determines how long the ADC
data must remain below the lower threshold before the FD_x
pins are reset to 0.
0x0 R/W
0x024C Fast detect dwell
MSB (local)
[7:0] Fast detect dwell time MSBs of the fast detect dwell time counter target. This is a load
value for a 16-bit counter that determines how long the ADC
data must remain below the lower threshold before the
FD_x pins are reset to 0.
0x0 R/W
0x026F Signal monitor
sync control
[7:2] Reserved Reserved. 0x0 R
1 Signal monitor next
synchronization mode
Signal monitor next synchronization mode. 0x0 R/W
0 Continuous mode.
1 Next synchronization mode. Only the next valid edge of the
SYSREF± pin is used to synchronize the signal monitor block.
Subsequent edges of the SYSREF± pin are ignored. When the
next SYSREF is found, Register 0x026F, Bit 0 clears. The SYSREF± pin
must be an integer multiple of the signal monitor period for
this function to operate correctly in continuous mode.
0 Signal monitor
synchronization mode
Signal monitor synchronization enable 0x0 R/W
0 Synchronization disabled.
1 If Register 0x026F, Bit 1 = 1, only the next valid edge of the
SYSREF± pin is used to synchronize the signal monitor block.
Subsequent edges of the SYSREF± pin are ignored. When the
next SYSREF signal is received, this bit is cleared. The SYSREF± input
pin must be enabled to synchronize the signal monitor blocks.
0x0270 Signal monitor
control (local)
[7:2] Reserved Reserved. 0x0 R
1 Peak detector 0x0 R/W
0 Peak detector disabled.
1 Peak detector enabled.
0 Reserved Reserved. 0x0 R
0x0271 Signal Monitor
Period 0 (local)
[7:0] Signal monitor period
[7:0]
Bits[7:0] of the 24-bit value that sets the number of output
clock cycles over which the signal monitor performs its
operation. Only even values are supported.
0x80 R/W
AD9208 Data Sheet
Rev. 0 | Page 100 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0272 Signal Monitor
Period 1 (local)
[7:0] Signal monitor period
[15:8]
Bits[15:8] of the 24-bit value that sets the number of output
clock cycles over which the signal monitor performs its
operation. Only even values are supported.
0x0 R/W
0x0273 Signal Monitor
Period 2 (local)
[7:0] Signal monitor period
[23:16]
Bits[23:16] of the 24-bit value that sets the number of output
clock cycles over which the signal monitor performs its
operation. Only even values are supported.
0x0 R/W
0x0274 Signal monitor
status control
(local)
[7:5] Reserved Reserved. 0x0 R
4 Result update 0x0 R/WC
1 Update signal monitor status registers, Register 0x0275 to
Register 0x0278. Self clearing.
3 Reserved Reserved. 0x0 R
[2:0] Result selection 0x1 R/W
001 Peak detector placed on status readback signals.
0x0275 Signal Monitor
Status 0 (local)
[7:0] Signal monitor result [7:0] Signal monitor status result. This 20-bit value contains the
status result calculated by the signal monitor block.
0x0 R
0x0276 Signal Monitor
Status 1 (local)
[7:0] Signal monitor result
[15:8]
Signal monitor status result. 0x0 R
0x0277 Signal Monitor
Status 2 (local)
[7:4] Reserved Reserved. 0x0 R
[3:0] Signal monitor result
[19:16]
Signal monitor status result. 0x0 R
0x0278 Signal monitor
status frame
counter (local)
[7:0] Period count result,
Bits[7:0]
Signal monitor frame counter status bits. Frame counter
increments whenever the period counter expires.
0x0 R
0x0279 Signal monitor
serial framer
control (local)
[7:2] Reserved Reserved. 0x0 R
[1:0] Signal monitor SPORT
over JESD204B enable
0x0 R/W
00 Disabled.
11 Enabled.
0x027A SPORT over
JESD204B input
selection (local)
[7:6] Reserved Reserved. 0x0 R
1 SPORT over JESD204B
input selection
Signal monitor serial framer input selection. When each
individual bit is a 1, the corresponding signal statistics
information is sent within the frame.
0x1 R/W
0 Disabled.
1 Peak detector data inserted in the serial frame.
0 Reserved Reserved. 0x0 R
DDC Function Registers (See the Digital Downconverter (DDC) Section)
0x0300 DDC SYNC control 7 DDC FTW/POW/MAW/
MBW update mode
Select DDC FTW/POW/MAW/MBW update mode. 0x0 R/W
0 Instantaneous/continuous update. FTW/POW/MAW/MBW
values are updated immediately.
1 FTW/POW/MAW/MBW values are updated synchronously when
the chip transfer bit (Register 0x000F, Bit 0) is set.
[6:5] Reserved Reserved. 0x0 R
4 DDC NCO soft reset This bit can be used to synchronize all the NCOs inside the DDC
blocks.
0x0 R/W
0 Normal operation.
1 DDC held in reset.
[3:2] Reserved Reserved. 0x0 R
Data Sheet AD9208
Rev. 0 | Page 101 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
1 DDC next
synchronization
0x0 R/W
0 Continuous mode. The SYSREF frequency must be an integer
multiple of the NCO frequency for this function to operate
correctly in continuous mode.
1 Only the next valid edge of the SYSREF± pin is used to
synchronize the NCO in the DDC block. Subsequent edges of
the SYSREF± pin are ignored. When the next SYSREF signal is
found, the DDC synchronization enable bit (Register 0x0300,
Bit 0) is cleared.
0 DDC synchronization
mode
The SYSREF input pin must be enabled to synchronize the DDCs. 0x0 R/W
0 Synchronization disabled.
1 If DDC next synchronization (Register 0x0300, Bit 1 = 1), only
the next valid edge of the SYSREF± pin is used to synchronize
the NCO in the DDC block. Subsequent edges of the SYSREF±
pin are ignored. When the next SYSREF signal is received, this
bit is cleared.
0x0310 DDC0 control 7 DDC0 mixer select 0x0 R/W
0 Real mixer (I and Q inputs must be from the same real channel).
1 Complex mixer (I and Q must be from separate, real and imaginary
quadrature ADC receive channels; analog demodulator).
6 DDC0 gain select Gain can be used to compensate for the 6 dB loss associated
with mixing an input signal down to baseband and filtering out
its negative component.
0x0 R/W
0 0 dB gain.
1 6 dB gain (multiply by 2).
[5:4] DDC0 intermediate
frequency (IF) mode
0x0 R/W
00 Variable IF mode.
01 0 Hz IF mode.
10 fS Hz IF mode.
11 Test mode.
3 DDC0 complex to real
enable
0x0 R/W
0 Complex (I and Q) outputs contain valid data.
1 Real (I) output only. complex to real enabled. Uses extra fS
mixing to convert to real.
[2:0] DDC0 decimation rate
select
Decimation filter selection. 0x0 R/W
000 HB1 + HB2 filter selection: decimate by 2 (complex to real
enabled), or decimate by 4 (complex to real disabled).
001 HB1 + HB2 + HB3 filter selection: decimate by 4 (complex to
real enabled), or decimate by 8 (complex to real disabled).
010 HB1 + HB2 + HB3 + HB4 filter selection: decimate by 8
(complex to real enabled), or decimate by 16 (complex to real
disabled).
011 HB1 filter selection: decimate by 1 (complex to real enabled), or
decimate by 2 (complex to real disabled).
100 HB1 + TB2 filter selection: decimate by 3 (complex to real
enabled), or decimate by 6 (complex to real disabled).
101 HB1 + HB2 + TB2 filter selection: decimate by 6 (complex to real
enabled), or decimate by 12 (complex to real disabled).
110 HB1 + HB2 + HB3 + TB2 filter selection: decimate by 12 (complex to
real enabled), or decimate by 24 (complex to real disabled).
111 Decimation determined by Register 0x0311, Bits[7:4].
AD9208 Data Sheet
Rev. 0 | Page 102 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0311 DDC0 input select [7:4] DDC0 decimation rate
select
Only valid when Register 0x0310, Bits[2:0] = 3'b111. 0x0 R/W
0 TB2 + HB4 + HB3 + HB2 + HB1 filter selection: decimate by 48
(complex to real disabled), or decimate by 24 (complex to real
enabled).
10 FB2 + HB1 filter selection: decimate by 10 (complex to real
disabled), or decimate by 5 (complex to real enabled).
11 FB2 + HB2 + HB1 filter selection: decimate by 20 (complex to
real disabled), or decimate by 10 (complex to real enabled).
100 FB2 + HB3 + HB2 + HB1 filter selection: decimate by 40 (complex to
real disabled), or decimate by 20 (complex to real enabled).
111 TB1 filter selection: decimate by 3 (decimate by 1.5 not supported).
1000 FB2 + TB1 filter selection: decimate by 15 (decimate by 7.5 not
supported).
1001 HB2 + FB2 + TB1 filter selection: decimate by 30 (decimate by
15 not supported).
3 Reserved Reserved. 0x0 R
2 DDC0 Q input select 0x0 R/W
0 Channel A.
1 Channel B.
1 Reserved Reserved. 0x0 R
0 DDC0 I input select 0x0 R/W
0 Channel A.
1 Channel B.
0x0314 DDC0 NCO control [7:4] DDC0 NCO channel select
mode
For edge control, the internal counter wraps after the
Register 0x0314, Bits[3:0] value is reached.
0x0 R/W
0 Use Register 0x0314, Bits[3:0].
1 2'b0, GPIO_B0, GPIO_A0.
10 2'b0, GPIO_B1, GPIO_A1.
11 2'b00, GPIO_A1, GPIO_A0.
100 2'b00, GPIO_B1, GPIO_B0.
101 GPIO_B1, GPIO_A1, GPIO_B0, GPIO_A0.
110 GPIO_B1, GPIO_B0, GPIO_A1, GPIO_A0.
1000 Increment internal counter on rising edge of the GPIO_A0 pin.
1001 Increment internal counter on rising edge of the GPIO_A1 pin.
1010 Increment internal counter on rising edge of the GPIO_B0 pin.
1011 Increment internal counter on rising edge of the GPIO_B1 pin.
[3:0] DDC0 NCO register map
channel select
NCO channel select register map control. 0x0 R/W
0 Select NCO Channel 0.
1 Select NCO Channel 1.
10 Select NCO Channel 2.
11 Select NCO Channel 3.
100 Select NCO Channel 4.
101 Select NCO Channel 5.
110 Select NCO Channel 6.
111 Select NCO Channel 7.
1000 Select NCO Channel 8.
1001 Select NCO Channel 9.
1010 Select NCO Channel 10.
1011 Select NCO Channel 11.
1100 Select NCO Channel 12.
1101 Select NCO Channel 13.
1110 Select NCO Channel 14.
1111 Select NCO Channel 15.
Data Sheet AD9208
Rev. 0 | Page 103 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0315 DDC0 phase
control
[7:4] Reserved Reserved. 0x0 R
[3:0] DDC0 phase update
index
Indexes the NCO channel whose phase and offset is updated.
The update method is based on the DDC phase update mode,
which can be continuous or require chip transfer.
0x0 R/W
0000 Update NCO Channel 0.
0001 Update NCO Channel 1.
0010 Update NCO Channel 2.
0011 Update NCO Channel 3.
0x0316 DDC0 Phase
Increment 0
[7:0] DDC0 phase increment
[7:0]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x0317 DDC0 Phase
Increment 1
[7:0] DDC0 phase increment
[15:8]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x0318 DDC0 Phase
Increment 2
[7:0] DDC0 phase increment
[23:16]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x0319 DDC0 Phase
Increment 3
[7:0] DDC0 phase increment
[31:24]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x031A DDC0 Phase
Increment 4
[7:0] DDC0 phase increment
[39:32]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x031B DDC0 Phase
Increment 5
[7:0] DDC0 phase increment
[47:40]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x031D DDC0 Phase Offset 0 [7:0] DDC0 phase offset [7:0] Twos complement phase offset value for the NCO. 0x0 R/W
0x031E DDC0 Phase Offset 1 [7:0] DDC0 phase offset [15:8] Twos complement phase offset value for the NCO. 0x0 R/W
0x031F DDC0 Phase Offset 2 [7:0] DDC0 phase offset [23:16] Twos complement phase offset value for the NCO. 0x0 R/W
0x0320 DDC0 Phase Offset 3 [7:0] DDC0 phase offset [31:24] Twos complement phase offset value for the NCO. 0x0 R/W
0x0321 DDC0 Phase Offset 4 [7:0] DDC0 phase offset [39:32] Twos complement phase offset value for the NCO. 0x0 R/W
0x0322 DDC0 Phase Offset 5 [7:0] DDC0 phase offset [47:40] Twos complement phase offset value for the NCO. 0x0 R/W
0x0327 DDC0 test enable [7:3] Reserved Reserved. 0x0 R
2 DDC0 Q output test
mode enable
Q samples always use the Test Mode B block. The test mode is
selected using the channel dependent Register 0x0550, Bits[3:0].
0x0 R/W
0 Test mode disabled.
1 Test mode enabled.
1 Reserved Reserved. 0x0 R
0 DDC0 I output test mode
enable
I samples always use the Test Mode A block. The test mode is
selected using the channel dependent Register 0x0550, Bits[3:0].
0x0 R/W
0 Test mode disabled.
1 Test mode enabled.
0x0330 DDC1 control 7 DDC1 mixer select 0x0 R/W
0 Real mixer (I and Q inputs must be from the same real channel).
1 Complex mixer (I and Q must be from separate, real and imaginary
quadrature ADC receive channels; analog demodulator).
6 DDC1 gain select Gain can be used to compensates for the 6 dB loss associated
with mixing an input signal down to baseband and filtering out
its negative component.
0x0 R/W
0 0 dB gain.
1 6 dB gain (multiply by 2).
[5:4] DDC1 intermediate
frequency (IF) mode
0x0 R/W
00 Variable IF mode.
01 0 Hz IF mode.
10 fS Hz IF mode.
11 Test mode.
3 DDC1 complex to real
enable
0x0 R/W
0 Complex (I and Q) outputs contain valid data.
1 Real (I) output only. Complex to real enabled. Uses extra fS
mixing to convert to real.
AD9208 Data Sheet
Rev. 0 | Page 104 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
[2:0] DDC1 decimation rate
select
Decimation filter selection. 0x0 R/W
000 HB1 + HB2 filter selection: decimate by 2 (complex to real
enabled), or decimate by 4 (complex to real disabled).
001 HB1 + HB2 + HB3 filter selection: decimate by 4 (complex to
real enabled), or decimate by 8 (complex to real disabled).
010 HB1 + HB2 + HB3 + HB4 filter selection: decimate by 8
(complex to real enabled), or decimate by 16 (complex to real
disabled).
011 HB1 filter selection: decimate by 1 (complex to real enabled), or
decimate by 2 (complex to real disabled).
100 HB1 + TB2 filter selection: decimate by 3 (complex to real
enabled), or decimate by 6 (complex to real disabled).
101 HB1 + HB2 + TB2 filter selection: decimate by 6 (complex to real
enabled), or decimate by 12 (complex to real disabled).
110 HB1 + HB2 + HB3 + TB2 filter selection: decimate by 12 (complex
to real enabled), or decimate by 24 (complex to real disabled).
111 Decimation determined by Register 0x0331, Bits[7:4].
0x0331 DDC1 input select [7:4] DDC1 decimation rate
select
Only valid when Register 0x0310, Bits[2:0] = 3'b111. 0x0 R/W
0 TB2 + HB4 + HB3 + HB2 + HB1 filter selection: decimate by 48
(complex to real disabled), or decimate by 24 (complex to real
enabled).
10 FB2 + HB1 filter selection: decimate by 10 (complex to real
disabled), or decimate by 5 (complex to real enabled).
11 FB2 + HB2 + HB1 filter selection: decimate by 20 (complex to
real disabled), or decimate by 10 (complex to real enabled).
100 FB2 + HB3 + HB2 + HB1 filter selection: decimate by 40 (complex
to real disabled), or decimate by 20 (complex to real enabled).
111 TB1 filter selection: decimate by 3 (decimate by 1.5 not supported).
1000 FB2 + TB1 filter selection: decimate by 15 (decimate by 7.5 not
supported).
1001 HB2 + FB2 + TB1 filter selection: decimate by 30 (decimate by
15 not supported).
3 Reserved Reserved. 0x0 R
2 DDC1 Q input select 0x1 R/W
0 Channel A.
1 Channel B.
1 Reserved Reserved. 0x0 R
0 DDC1 I input select 0x1 R/W
0 Channel A.
1 Channel B.
0x0334 DDC1 NCO control [7:4] DDC1 NCO channel select
mode
For edge control, the internal counter wraps when the
Register 0x0334, Bits[3:0] value is reached.
0x0 R/W
0 Use Register 0x0314, Bits[3:0]
1 2'b0, GPIO_B0, GPIO_A0.
10 2'b0, GPIO_B1, GPIO_A1.
11 2'b00, GPIO_A1, GPIO_A0.
100 2'b00, GPIO_B1, GPIO_B0.
101 GPIO_B1, GPIO_A1, GPIO_B0, GPIO_A0.
110 GPIO_B1, GPIO_B0, GPIO_A1, GPIO_A0.
1000 Increment internal counter when rising edge of the GPIO_A0 pin.
1001 Increment internal counter when rising edge of the GPIO_A1 pin.
1010 Increment internal counter when rising edge of the GPIO_B0 pin.
1011 Increment internal counter when rising edge of the GPIO_B1 pin.
Data Sheet AD9208
Rev. 0 | Page 105 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
[3:0] DDC1 NCO register map
channel select
NCO channel select register map control 0x0 R/W
0 Select NCO Channel 0.
1 Select NCO Channel 1.
10 Select NCO Channel 2.
11 Select NCO Channel 3.
100 Select NCO Channel 4.
101 Select NCO Channel 5.
110 Select NCO Channel 6.
111 Select NCO Channel 7.
1000 Select NCO Channel 8.
1001 Select NCO Channel 9.
1010 Select NCO Channel 10.
1011 Select NCO Channel 11.
1100 Select NCO Channel 12.
1101 Select NCO Channel 13.
1110 Select NCO Channel 14.
1111 Select NCO Channel 15.
0x0335 DDC1 phase
control
[7:4] Reserved Reserved. 0x0 R
[3:0] DDC1 phase update
index
Indexes the NCO channel for which the phase and offset is to
be updated. The update method is based on the DDC phase
update mode, which can be continuous or require chip transfer.
0x0 R/W
0000 Update NCO Channel 0.
0001 Update NCO Channel 1.
0010 Update NCO Channel 2.
0011 Update NCO Channel 3.
0x0336 DDC1 Phase
Increment 0
[7:0] DDC1 phase increment
[7:0]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x0337 DDC1 Phase
Increment 1
[7:0] DDC1 phase increment
[15:8]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x0338 DDC1 Phase
Increment 2
[7:0] DDC1 phase increment
[23:16]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x0339 DDC1 Phase
Increment 3
[7:0] DDC1 phase increment
[31:24]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x033A DDC1 Phase
Increment 4
[7:0] DDC1 phase increment
[39:32]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x033B DDC1 Phase
Increment 5
[7:0] DDC1 phase increment
[47:40]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x033D DDC1 Phase
Offset 0
[7:0] DDC1 phase offset [7:0] Twos complement phase offset value for the NCO. 0x0 R/W
0x033E DDC1 Phase
Offset 1
[7:0] DDC1 phase offset [15:8] Twos complement phase offset value for the NCO. 0x0 R/W
0x033F DDC1 Phase
Offset 2
[7:0] DDC1 phase offset [23:16] Twos complement phase offset value for the NCO. 0x0 R/W
0x0340 DDC1 Phase
Offset 3
[7:0] DDC1 phase offset [31:24] Twos complement phase offset value for the NCO. 0x0 R/W
0x0341 DDC1 Phase
Offset 4
[7:0] DDC1 phase offset [39:32] Twos complement phase offset value for the NCO. 0x0 R/W
0x0342 DDC1 Phase
Offset 5
[7:0] DDC1 phase offset [47:40] Twos complement phase offset value for the NCO. 0x0 R/W
0x0347 DDC1 test enable [7:3] Reserved Reserved. 0x0 R
2 DDC1 Q output test
mode enable
Q samples always use the Test Mode B block. The test mode is
selected using the channel dependent Register 0x0550, Bits[3:0].
0x0 R/W
0 Test mode disabled.
1 Test mode enabled.
1 Reserved Reserved. 0x0 R
0 DDC1 I output test mode
enable
I samples always use the Test Mode A block. The test mode is
selected using the channel dependent Register 0x0550, Bits[3:0].
0x0 R/W
0 Test mode disabled.
1 Test mode enabled.
AD9208 Data Sheet
Rev. 0 | Page 106 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0350 DDC2 control 7 DDC2 mixer select 0x0 R/W
0 Real mixer (I and Q inputs must be from the same real channel)
1 Complex mixer (I and Q must be from separate, real and imaginary
quadrature ADC receive channels; analog demodulator)
6 DDC2 gain select Gain can be used to compensates for the 6 dB loss associated
with mixing an input signal down to baseband and filtering out
its negative component.
0x0 R/W
0 0 dB gain.
1 6 dB gain (multiply by 2).
[5:4] DDC2 intermediate
frequency (IF) mode
0x0 R/W
00 Variable IF mode.
01 0 Hz IF mode.
10 fS Hz IF mode.
11 Test mode.
3 DDC2 complex to real
enable
0x0 R/W
0 Complex (I and Q) outputs contain valid data.
1 Real (I) output only. Complex to real enabled. Uses extra fS
mixing to convert to real.
[2:0] DDC2 decimation rate
select
Decimation filter selection. 0x0 R/W
000 HB1 + HB2 filter selection: decimate by 2 (complex to real
enabled), or decimate by 4 (complex to real disabled).
001 HB1 + HB2 + HB3 filter selection: decimate by 4 (complex to
real enabled), or decimate by 8 (complex to real disabled).
010 HB1 + HB2 + HB3 + HB4 filter selection: decimate by 8
(complex to real enabled), or decimate by 16 (complex to real
disabled).
011 HB1 filter selection: decimate by 1 (complex to real enabled), or
decimate by 2 (complex to real disabled).
100 HB1 + TB2 filter selection: decimate by 3 (complex to real
enabled), or decimate by 6 (complex to real disabled).
101 HB1 + HB2 + TB2 filter selection: decimate by 6 (complex to real
enabled), or decimate by 12 (complex to real disabled).
110 HB1 + HB2 + HB3 + TB2 filter selection: decimate by 12 (complex to
real enabled), or decimate by 24 (complex to real disabled).
111 Decimation determined by Register 0x0351, Bits[7:4].
0x0351 DDC2 input select [7:4] DDC2 decimation rate
select
Only valid when Register 0x0310, Bits[2:0] = 3'b111. 0x0 R/W
0 TB2 + HB4 + HB3 + HB2 + HB1 filter selection: decimate by 48
(complex to real disabled), or decimate by 24 (complex to real
enabled).
10 FB2 + HB1 filter selection: decimate by 10 (complex to real
disabled), or decimate by 5 (complex to real enabled).
11 FB2 + HB2 + HB1 filter selection: decimate by 20 (complex to
real disabled), or decimate by 10 (complex to real enabled).
100 FB2 + HB3 + HB2 + HB1 filter selection: decimate by 40 (complex to
real disabled), or decimate by 20 (complex to real enabled).
3 Reserved Reserved. 0x0 R
2 DDC2 Q input select 0x0 R/W
0 Channel A.
1 Channel B.
1 Reserved Reserved. 0x0 R
0 DDC2 I input select 0x0 R/W
0 Channel A.
1 Channel B.
Data Sheet AD9208
Rev. 0 | Page 107 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0354 DDC2 NCO control [7:4] DDC2 NCO channel select
mode
For edge control, the internal counter wraps when the
Register 0x0354, Bits[3:0] value is reached.
0x0 R/W
0 Use 0x0314[3:0]
1 2'b0, GPIO B0, GPIO A0.
10 2'b0, GPIO B1, GPIO A1.
11 2'b00, GPIO A1, GPIO A0.
100 2'b00, GPIO B1, GPIO B0.
101 GPIO B1, GPIO A1, GPIO B0, GPIO A0.
110 GPIO B1, GPIO B0, GPIO A1, GPIO A0.
1000 Increment internal counter when rising edge of the GPIO_A0 pin.
1001 Increment internal counter when rising edge of the GPIO_A1 pin.
1010 Increment internal counter when rising edge of the GPIO_B0 pin.
1011 Increment internal counter when rising edge of the GPIO_B1 pin.
[3:0] DDC2 NCO register map
channel select
NCO channel select register map control. 0x0 R/W
0 Select NCO Channel 0.
1 Select NCO Channel 1.
10 Select NCO Channel 2.
11 Select NCO Channel 3.
100 Select NCO Channel 4.
101 Select NCO Channel 5.
110 Select NCO Channel 6.
111 Select NCO Channel 7.
1000 Select NCO Channel 8.
1001 Select NCO Channel 9.
1010 Select NCO Channel 10.
1011 Select NCO Channel 11.
1100 Select NCO Channel 12.
1101 Select NCO Channel 13.
1110 Select NCO Channel 14.
1111 Select NCO Channel 15.
0x0355 DDC2 phase
control
[7:4] Reserved Reserved. 0x0 R
[3:0] DDC2 phase update
index
Indexes the NCO channel whose phase and offset gets
updated. The update method is based on the DDC phase
update mode, which can be continuous or require chip
transfer.
0x0 R/W
0000 Update NCO Channel 0.
0001 Update NCO Channel 1.
0010 Update NCO Channel 2.
0011 Update NCO Channel 3.
0x0356 DDC2 Phase
Increment 0
[7:0] DDC2 phase increment
[7:0]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x0357 DDC2 Phase
Increment 1
[7:0] DDC2 phase increment
[15:8]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x0358 DDC2 Phase
Increment 2
[7:0] DDC2 phase increment
[23:16]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x0359 DDC2 Phase
Increment 3
[7:0] DDC2 phase increment
[31:24]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x035A DDC2 Phase
Increment 4
[7:0] DDC2 phase increment
[39:32]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x035B DDC2 Phase
Increment 5
[7:0] DDC2 phase increment
[47:40]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x035D DDC2 Phase
Offset 0
[7:0] DDC2 phase offset [7:0] Twos complement phase offset value for the NCO. 0x0 R/W
0x035E DDC2 Phase
Offset 1
[7:0] DDC2 phase offset [15:8] Twos complement phase offset value for the NCO. 0x0 R/W
0x035F DDC2 Phase
Offset 2
[7:0] DDC2 phase offset [23:16] Twos complement phase offset value for the NCO. 0x0 R/W
0x0360 DDC2 Phase
Offset 3
[7:0] DDC2 phase offset [31:24] Twos complement phase offset value for the NCO. 0x0 R/W
AD9208 Data Sheet
Rev. 0 | Page 108 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0361 DDC2 Phase
Offset 4
[7:0] DDC2 phase offset [39:32] Twos complement phase offset value for the NCO. 0x0 R/W
0x0362 DDC2 Phase
Offset 5
[7:0] DDC2 phase offset [47:40] Twos complement phase offset value for the NCO. 0x0 R/W
0x0367 DDC2 test enable [7:3] Reserved Reserved. 0x0 R
2 DDC2 Q output test
mode enable
Q samples always use the Test Mode B block. The test mode is
selected using the channel dependent Register 0x0550, Bits[3:0].
0x0 R/W
0 Test mode disabled.
1 Test mode enabled.
1 Reserved Reserved. 0x0 R
0 DDC2 I output test mode
enable
I samples always use the Test Mode A block. The test mode is
selected using the channel dependent Register 0x0550, Bits[3:0].
0x0 R/W
0 Test mode disabled.
1 Test mode enabled.
0x0370 DDC3 control 7 DDC3 mixer select 0x0 R/W
0 Real mixer (I and Q inputs must be from the same real channel).
1 Complex mixer (I and Q must be from separate, real and imaginary
quadrature ADC receive channels; analog demodulator).
6 DDC3 gain select Gain can be used to compensate for the 6 dB loss associated
with mixing an input signal down to baseband and filtering out
its negative component.
0x0 R/W
0 0 dB gain.
1 6 dB gain (multiply by 2)
[5:4] DDC3 intermediate
frequency (IF) mode
0x0 R/W
00 Variable IF mode.
01 0 Hz IF mode.
10 fS Hz IF mode.
11 Test mode.
3 DDC3 complex to real
enable
0x0 R/W
0 Complex (I and Q) outputs contain valid data.
1 Real (I) output only. complex to real enabled. Uses extra fS
mixing to convert to real.
[2:0] DDC3 decimation rate
select
Decimation filter selection. 0x0 R/W
000 HB1 + HB2 filter selection: decimate by 2 (complex to real
enabled), or decimate by 4 (complex to real disabled).
001 HB1 + HB2 + HB3 filter selection: decimate by 4 (complex to
real enabled), or decimate by 8 (complex to real disabled).
010 HB1 + HB2 + HB3 + HB4 filter selection: decimate by 8
(complex to real enabled), or decimate by 16 (complex to real
disabled).
011 HB1 filter selection: decimate by 1 (complex to real enabled), or
decimate by 2 (complex to real disabled).
100 HB1 + TB2 filter selection: decimate by 3 (complex to real
enabled), or decimate by 6 (complex to real disabled).
101 HB1 + HB2 + TB2 filter selection: decimate by 6 (complex to real
enabled), or decimate by 12 (complex to real disabled).
110 HB1 + HB2 + HB3 + TB2 filter selection: decimate by 12 (complex to
real enabled), or decimate by 24 (complex to real disabled).
111 Decimation determined by Register 0x0371, Bits[7:4].
Data Sheet AD9208
Rev. 0 | Page 109 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0371 DDC3 input select [7:4] DDC3 decimation rate
select
Only valid when Register 0x0310, Bits[2:0] = 3'b111. 0x0 R/W
0 TB2 + HB4 + HB3 + HB2 + HB1 filter selection: decimate by 48
(complex to real disabled), or decimate by 24 (complex to real
enabled).
10 FB2 + HB1 filter selection: decimate by 10 (complex to real
disabled), or decimate by 5 (complex to real enabled)
11 FB2 + HB2 + HB1 filter selection: decimate by 20 (complex to real
disabled), or decimate by 10 (complex to real enabled)
100 FB2 + HB3 + HB2 + HB1 filter selection: decimate by 40 (complex
to real disabled), or decimate by 20 (complex to real enabled)
3 Reserved Reserved. 0x0 R
2 DDC3 Q input select 0x1 R/W
0 Channel A.
1 Channel B.
1 Reserved Reserved. 0x0 R
0 DDC3 I input select 0x1 R/W
0 Channel A.
1 Channel B.
0x0374 DDC3 NCO control [7:4] DDC3 NCO channel select
mode
For edge control, the internal counter wraps when the
Register 0x0374, Bits[3:0] value is reached.
0x0 R/W
0 Use Register 0x0314, Bits[3:0].
1 2'b0, GPIO B0, GPIO A0.
10 2'b0, GPIO B1, GPIO A1.
11 2'b00, GPIO A1, GPIO A0.
100 2'b00, GPIO B1, GPIO B0.
101 GPIO B1, GPIO A1, GPIO B0, GPIO A0.
110 GPIO B1, GPIO B0, GPIO A1, GPIO A0.
1000 Increment internal counter when rising edge of GPIO_A0 pin.
1001 Increment internal counter when rising edge of GPIO_A1 pin.
1010 Increment internal counter when rising edge of GPIO_B0 pin.
1011 Increment internal counter when rising edge of GPIO_B1 pin.
[3:0] DDC3 NCO register map
channel select
NCO channel select register map control. 0x0 R/W
0 Select NCO Channel 0.
1 Select NCO Channel 1.
10 Select NCO Channel 2.
11 Select NCO Channel 3.
100 Select NCO Channel 4.
101 Select NCO Channel 5.
110 Select NCO Channel 6.
111 Select NCO Channel 7.
1000 Select NCO Channel 8.
1001 Select NCO Channel 9.
1010 Select NCO Channel 10.
1011 Select NCO Channel 11.
1100 Select NCO Channel 12.
1101 Select NCO Channel 13.
1110 Select NCO Channel 14.
1111 Select NCO Channel 15.
0x0375 DDC3 phase
control
[7:4] Reserved Reserved. 0x0 R
[3:0] DDC3 phase update
index
Indexes the NCO channel whose phase and offset gets
updated. The update method is based on the DDC phase
update mode, which can be continuous or require chip
transfer.
0x0 R/W
0000 Update NCO Channel 0.
0001 Update NCO Channel 1.
0010 Update NCO Channel 2.
0011 Update NCO Channel 3.
AD9208 Data Sheet
Rev. 0 | Page 110 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0376 DDC3 Phase
Increment 0
[7:0] DDC3 phase increment
[7:0]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x0377 DDC3 Phase
Increment 1
[7:0] DDC3 phase increment
[15:8]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248
0x0 R/W
0x0378 DDC3 Phase
Increment 2
[7:0] DDC3 phase increment
[23:16]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x0379 DDC3 Phase
Increment 3
[7:0] DDC3 phase increment
[31:24]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x037A DDC3 Phase
Increment 4
[7:0] DDC3 phase increment
[39:32]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x037B DDC3 Phase
Increment 5
[7:0] DDC3 phase increment
[47:40]
FTW. Twos complement phase increment value for the NCO.
Complex mixing frequency = (DDC phase increment × fS)/248.
0x0 R/W
0x037D DDC3 Phase
Offset 0
[7:0] DDC3 phase offset [7:0] Twos complement phase offset value for the NCO. 0x0 R/W
0x037E DDC3 Phase
Offset 1
[7:0] DDC3 phase offset [15:8] Twos complement phase offset value for the NCO. 0x0 R/W
0x037F DDC3 Phase
Offset 2
[7:0] DDC3 phase offset [23:16] Twos complement phase offset value for the NCO. 0x0 R/W
0x0380 DDC3 Phase
Offset 3
[7:0] DDC3 phase offset [31:24] Twos complement phase offset value for the NCO. 0x0 R/W
0x0381 DDC3 Phase
Offset 4
[7:0] DDC3 phase offset [39:32] Twos complement phase offset value for the NCO. 0x0 R/W
0x0382 DDC3 Phase
Offset 5
[7:0] DDC3 phase offset [47:40] Twos complement phase offset value for the NCO. 0x0 R/W
0x0387 DDC3 test enable [7:3] Reserved Reserved. 0x0 R
2 DDC3 Q output test
mode enable
Q samples always use the Test Mode B block. The test mode is
selected using the channel dependent Register 0x0550, Bits[3:0].
0x0 R/W
0 Test mode disabled.
1 Test mode enabled.
1 Reserved Reserved. 0x0 R
0 DDC3 I output test mode
enable
I samples always use the Test Mode A block. The test mode is
selected using the channel dependent Register 0x0550, Bits[3:0].
0x0 R/W
0 Test mode disabled.
1 Test mode enabled.
0x0390 DDC0 Phase
Increment
Fractional A0
[7:0] DDC0 Phase Increment
Fractional A [7:0]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x0391 DDC0 Phase
Increment
Fractional A1
[7:0] DDC0 Phase Increment
Fractional A [15:8]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x0392 DDC0 Phase
Increment
Fractional A2
[7:0] DDC0 Phase Increment
Fractional A [23:16]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x0393 DDC0 Phase
Increment
Fractional A3
[7:0] DDC0 Phase Increment
Fractional A [31:24]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x0394 DDC0 Phase
Increment
Fractional A4
[7:0] DDC0 Phase Increment
Fractional A [39:32]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x0395 DDC0 Phase
Increment
Fractional A5
[7:0] DDC0 Phase Increment
Fractional A [47:40]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x0398 DDC0 Phase
Increment
Fractional B0
[7:0] DDC0 Phase Increment
Fractional B [7:0]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x0399 DDC0 Phase
Increment
Fractional B1
[7:0] DDC0 Phase Increment
Fractional B [15:8]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x039A DDC0 Phase
Increment
Fractional B2
[7:0] DDC0 Phase Increment
Fractional B [23:16]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x039B DDC0 Phase
Increment
Fractional B3
[7:0] DDC0 Phase Increment
Fractional B [31:24]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
Data Sheet AD9208
Rev. 0 | Page 111 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x039C DDC0 Phase
Increment
Fractional B4
[7:0] DDC0 Phase Increment
Fractional B [39:32]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x039D DDC0 Phase
Increment
Fractional B5
[7:0] DDC0 Phase Increment
Fractional B [47:40]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03A0 DDC1 Phase
Increment
Fractional A0
[7:0] DDC1 Phase Increment
Fractional A [7:0]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03A1 DDC1 Phase
Increment
Fractional A1
[7:0] DDC1 Phase Increment
Fractional A [15:8]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03A2 DDC1 Phase
Increment
Fractional A2
[7:0] DDC1 Phase Increment
Fractional A [23:16]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03A3 DDC1 Phase
Increment
Fractional A3
[7:0] DDC1 Phase Increment
Fractional A [31:24]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03A4 DDC1 Phase
Increment
Fractional A4
[7:0] DDC1 Phase Increment
Fractional A [39:32]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03A5 DDC1 Phase
Increment
Fractional A5
[7:0] DDC1 Phase Increment
Fractional A [47:40]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03A8 DDC1 Phase
Increment
Fractional B0
[7:0] DDC1 Phase Increment
Fractional B [7:0]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03A9 DDC1 Phase
Increment
Fractional B1
[7:0] DDC1 Phase Increment
Fractional B [15:8]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03AA DDC1 Phase
Increment
Fractional B2
[7:0] DDC1 Phase Increment
Fractional B [23:16]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03AB DDC1 Phase
Increment
Fractional B3
[7:0] DDC1 Phase Increment
Fractional B [31:24]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03AC DDC1 Phase
Increment
Fractional B4
[7:0] DDC1 Phase Increment
Fractional B [39:32]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03AD DDC1 Phase
Increment
Fractional B5
[7:0] DDC1 Phase Increment
Fractional B [47:40]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03B0 DDC2 Phase
Increment
Fractional A0
[7:0] DDC2 Phase Increment
Fractional A [7:0]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03B1 DDC2 Phase
Increment
Fractional A1
[7:0] DDC2 Phase Increment
Fractional A [15:8]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03B2 DDC2 Phase
Increment
Fractional A2
[7:0] DDC2 Phase Increment
Fractional A [23:16]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03B3 DDC2 Phase
Increment
Fractional A3
[7:0] DDC2 Phase Increment
Fractional A [31:24]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03B4 DDC2 Phase
Increment
Fractional A4
[7:0] DDC2 Phase Increment
Fractional A [39:32]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03B5 DDC2 Phase
Increment
Fractional A5
[7:0] DDC2 Phase Increment
Fractional A [47:40]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03B8 DDC2 Phase
Increment
Fractional B0
[7:0] DDC2 Phase Increment
Fractional B [7:0]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03B9 DDC2 Phase
Increment
Fractional B1
[7:0] DDC2 Phase Increment
Fractional B [15:8]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
AD9208 Data Sheet
Rev. 0 | Page 112 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x03BA DDC2 Phase
Increment
Fractional B2
[7:0] DDC2 Phase Increment
Fractional B [23:16]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03BB DDC2 Phase
Increment
Fractional B3
[7:0] DDC2 Phase Increment
Fractional B [31:24]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03BC DDC2 Phase
Increment
Fractional B4
[7:0] DDC2 Phase Increment
Fractional B [39:32]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03BD DDC2 Phase
Increment
Fractional B5
[7:0] DDC2 Phase Increment
Fractional B [47:40]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03C0 DDC3 Phase
Increment
Fractional A0
[7:0] DDC3 Phase Increment
Fractional A [7:0]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03C1 DDC3 Phase
Increment
Fractional A1
[7:0] DDC3 Phase Increment
Fractional A [15:8]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03C2 DDC3 Phase
Increment
Fractional A2
[7:0] DDC3 Phase Increment
Fractional A [23:16]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03C3 DDC3 Phase
Increment
Fractional A3
[7:0] DDC3 Phase Increment
Fractional A [31:24]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03C4 DDC3 Phase
Increment
Fractional A4
[7:0] DDC3 Phase Increment
Fractional A [39:32]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03C5 DDC3 Phase
Increment
Fractional A5
[7:0] DDC3 Phase Increment
Fractional A [47:40]
Numerator correction term for Modulus Phase Accumulator A. 0x0 R/W
0x03C8 DDC3 Phase
Increment
Fractional B0
[7:0] DDC3 Phase Increment
Fractional B [7:0]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03C9 DDC3 Phase
Increment
Fractional B1
[7:0] DDC3 Phase Increment
Fractional B [15:8]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03CA DDC3 Phase
Increment
Fractional B2
[7:0] DDC3 Phase Increment
Fractional B [23:16]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03CB DDC3 Phase
Increment
Fractional B3
[7:0] DDC3 Phase Increment
Fractional B [31:24]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03CC DDC3 Phase
Increment
Fractional B4
[7:0] DDC3 Phase Increment
Fractional B [39:32]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
0x03CD DDC3 Phase
Increment
Fractional B5
[7:0] DDC3 Phase Increment
Fractional B [47:40]
Denominator correction term for Modulus Phase Accumulator B. 0x0 R/W
Digital Outputs and Test Modes Registers
0x0550 ADC test mode
control (local)
7 User pattern selection Test mode user pattern selection. This bit is only used when
Register 0x0550, Bits[3:0] = 4’b1000 (user input mode).
Otherwise, it is ignored. User Pattern 1 is found in the User
Pattern 1 MSB register (Register 0x0552) and the User Pattern 1
LSB (Register 0x0551) registers. User Pattern 2 is found in the
User Pattern 2 MSB register (Register 0x0554) and the User
Patter 2 LSB (Register 0x0553) register, and so on.
0x0 R/W
0 Continuous/repeat pattern. Place each user pattern (1, 2, 3, and
4) on the output for 1 clock cycle and then repeat. (Output User
Pattern 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, and so on.)
1 Single pattern. Place each user pattern (1, 2, 3, and 4) on the
output for 1 clock cycle and then output all zeros. (Output User
Pattern 1, 2, 3, 4, and then output all zeros)
6 Reserved Reserved. 0x0 R
5 Reset PN long generator Test mode long pseudorandom number test generator reset. 0x0 R/W
0 Long PN enabled.
1 Long PN held in reset.
Data Sheet AD9208
Rev. 0 | Page 113 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
4 Reset PN short generator Test mode short pseudorandom number test generator reset. 0x0 R/W
0 Short PN enabled.
1 Short PN held in reset.
[3:0] Test mode selection Test mode generation selection. 0x0 R/W
0000 Off (normal operation).
0001 Midscale short.
0010 Positive full scale.
0011 Negative full scale.
0100 Alternating checker board.
0101 PN sequence (long).
0110 PN sequence (short).
0111 1/0 word toggle.
1000 User pattern test mode (used with Register 0x0550, Bit 7 and
the User Pattern 1, User Pattern 2, User Pattern 3, and User
Pattern 4 registers).
1111 Ramp output.
0x0551 User Pattern 1 LSB [7:0] User Pattern 1 [7:0] User Test Pattern 1 least significant byte. 0x0 R/W
0x0552 User Pattern 1 MSB [7:0] User Pattern 1 [15:8] User Test Pattern 1 least significant byte. 0x0 R/W
0x0553 User Pattern 2 LSB [7:0] User Pattern 2 [7:0] User Test Pattern 2 least significant byte. 0x0 R/W
0x0554 User Pattern 2 MSB [7:0] User Pattern 2 [15:8] User Test Pattern 2 least significant byte. 0x0 R/W
0x0555 User Pattern 3 LSB [7:0] User Pattern 3 [7:0] User Test Pattern 3 least significant bits. 0x0 R/W
0x0556 User Pattern 3 MSB [7:0] User Pattern 3 [15:8] User Test Pattern 3 least significant bits. 0x0 R/W
0x0557 User Pattern 4 LSB [7:0] User Pattern 4 [7:0] User Test Pattern 4 least significant bits. 0x0 R/W
0x0558 User Pattern 4 MSB [7:0] User Pattern 4 [15:8] User Test Pattern 4 least significant bits. 0x0 R/W
0x0559 Output Mode
Control 1
[7:4] Converter control Bit 1
selection
0x0 R/W
0000 Tie low (1'b0).
0001 Overrange bit.
0010 Signal monitor bit .
0011 Fast detect (FD) bit.
0101 SYSREF.
[3:0] Converter control Bit 0
selection
0x0 R/W
0000 Tie low (1'b0).
0001 Overrange bit.
0010 Signal monitor bit.
0011 Fast detect (FD) bit.
0101 SYSREF.
0x055A Output Mode
Control 2
[7:4] Reserved Reserved. 0x0 R
[3:0] Converter control Bit 2
selection
0x1 R/W
0000 Tie low (1'b0).
0001 Overrange bit.
0010 Signal monitor bit.
0011 Fast detect (FD) bit.
0101 SYSREF.
0x0561 Out sample mode [7:3] Reserved Reserved. 0x0 R/W
2 Sample invert 0x0 R/W
0 ADC sample data is not inverted.
1 ADC sample data is inverted.
[1:0] Data format select 0x1 R/W
00 Offset binary.
01 Twos complement (default)
0x0562 Out overrange
clear
[7:0] Data format overrange
clear
Overrange clear bits (one bit for each virtual converter). Writing
a 1 to the overrange clear bit clears the corresponding
overrange sticky bit.
0x0 R/W
0 Overrange bit enabled.
1 Overrange bit cleared.
AD9208 Data Sheet
Rev. 0 | Page 114 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0563 Out overrange
status
[7:0] Data format overrange Overrange sticky bit status (one bit for each virtual converter).
Writing a 1 to the overrange clear bit clears the corresponding
overrange sticky bit.
0x0 R
0 No overrange occurred.
1 Overrange occurred.
0x0564 Out channel select [7:1] Reserved Reserved. 0x0 R
0 Converter channel swap
control
0x0 R/W
0 Normal channel ordering.
1 Channel swap enabled.
0x056E PLL control [7:4] JESD204B lane rate control 0x3 R/W
0000 Lane rate = 6.75 Gbps to 13.5 Gbps.
0001 Lane rate = 3.375 Gbps to 6.75 Gbps.
0011 Lane rate = 13.5 Gbps to 15.5 Gbps.
0101 Lane rate = 1.6875 Gbps to 3.375 Gbps.
[3:0] Reserved Reserved. 0x0 R
0x056F PLL status 7 PLL lock status 0x0 R
0 Not locked.
1 Locked.
[6:4] Reserved Reserved. 0x0 R
3 PLL loss of lock Loss of lock sticky bit.
1 Indicate a loss of lock has occurred at some time. Cleared by
setting Register 0x0571, Bit 0.
[2:0] Reserved Reserved
0x0570 fS × 4 configuration [7:0] See the fS × 4 Mode section. 0xFF R/W
0xFE L = 8, M = 2, F = 2, S = 4, N’ = 16, N = 16, CS = 0, CF = 0, HD = 0;
fS × 4 mode enabled.
0xFF fS × 4 mode disabled. L, M, and F set by Register 0x058B, Bits[4:0],
Register 0x58E, Bits[7:0], and Register 0x058C, Bits[7:0], respectively.
0x0571 JESD204B Link
Control 1
7 Standby mode 0x0 R/W
0 Standby mode forces zeros for all converter samples.
1 Standby mode forces code group synchronization (K28.5
characters).
6 Tail bit(t) PN 0x0 R/W
0 Disable.
1 Enable.
5 Long transport layer test 0x0 R/W
0 JESD204B test samples disabled.
1 JESD204B test samples enabled; long transport layer test
sample sequence (as specified in JESD204B Section 5.1.6.3)
sent on all link lanes.
4 Lane synchronization 0x1 R/W
0 Disable FACI uses /K28.7/.
1 Enable FACI uses /K28.3/ and /K28.7/.
[3:2] ILAS sequence mode 0x1 R/W
00 Initial lane alignment sequence disabled (JESD204B
Section 5.3.3.5).
01 Initial lane alignment sequence enabled (JESD204B Section 5.3.3.5).
11 Initial lane alignment sequence always on test mode. JESD204B
data link layer test mode where repeated lane alignment sequence
(as specified in JESD204B Section 5.3.3.8.2) sent on all lanes.
1 FACI 0x0 R/W
0 Frame alignment character insertion enabled (JESD204B
Section 5.3.3.4).
1 Frame alignment character insertion disabled. For debug only
(JESD204B Section 5.3.3.4).
Data Sheet AD9208
Rev. 0 | Page 115 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0 Link control 0x0 R/W
0 JESD204B serial transmit link enabled. Transmission of the
/K28.5/ characters for code group synchronization is controlled
by the SYNC~ signal.
1 JESD204B serial transmit link powered down (held in reset and
clock gated).
0x0572 JESD204B Link
Control 2
[7:6] SYNCINB± pin control 0x0 R/W
00 Normal mode.
10 Ignore SYNCINB± (force CGS).
11 Ignore SYNCINB± (force ILAS/user data).
5 SYNCINB± pin invert 0x0 R/W
0 SYNCINB± pin not inverted.
1 SYNCINB± pin inverted.
4 SYNCINB± pin type 0x0 R/W
0 LVDS differential pair SYNC~ input.
1 CMOS single-ended SYNC~ input. SYNCINB+ used.
3 Reserved Reserved. 0x0 R
2 8-bit/10-bit bypass 0x0 R/W
0 8-bit/10-bit enabled.
1 8-bit/10-bit bypassed (most significant 2 bits are 0).
1 8-bit/10-bit bit invert 0x0 R/W
0 Normal.
1 Invert a, b, c, d, e, f, g, h, I, and j symbols.
0 Reserved Reserved. 0x0 R/W
0x0573 JESD204B Link
Control 3
[7:6] Checksum mode 0x0 R/W
00 Checksum is the sum of all 8-bit registers in the link
configuration table.
01 Checksum is the sum of all individual link configuration fields
(LSB aligned).
10 Checksum is disabled (set to zero). For test purposes only.
11 Unused.
[5:4] Test injection point 0x0 R/W
0 N' sample input.
1 10-bit data at 8-bit/10-bit output (for PHY testing).
10 8-bit data at scrambler input.
[3:0] JESD204B test mode
patterns
0x0 R/W
0 Normal operation (test mode disabled).
1 Alternating checkerboard.
10 1/0 word toggle.
11 31-bit pseudorandom number (PN) sequence: x31 + x28 + 1.
100 23-bit PN sequence: x23 + x18 + 1.
101 15-bit PN sequence: x15 + x14 + 1.
110 9-bit PN sequence: x9 + x5 + 1.
111 7-bit PN sequence: x7 + x6 + 1.
1000 Ramp output.
1110 Continuous/repeat user test.
1111 Single user test.
AD9208 Data Sheet
Rev. 0 | Page 116 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0574 JESD204B Link
Control 4
[7:4] ILAS delay 0x0 R/W
0 Transmit ILAS on first LMFC after SYNCINB± deasserted.
1 Transmit ILAS on second LMFC after SYNCINB± deasserted.
10 Transmit ILAS on third LMFC after SYNCINB± deasserted.
11 Transmit ILAS on fourth LMFC after SYNCINB± deasserted.
100 Transmit ILAS on fifth LMFC after SYNCINB± deasserted.
101 Transmit ILAS on sixth LMFC after SYNCINB± deasserted.
110 Transmit ILAS on seventh LMFC after SYNCINB± deasserted.
111 Transmit ILAS on eighth LMFC after SYNCINB± deasserted.
1000 Transmit ILAS on ninth LMFC after SYNCINB± deasserted.
1001 Transmit ILAS on tenth LMFC after SYNCINB± deasserted.
1010 Transmit ILAS on eleventh LMFC after SYNCINB± deasserted.
1011 Transmit ILAS on twelfth LMFC after SYNCINB± deasserted.
1100 Transmit ILAS on thirteenth LMFC after SYNCINB± deasserted.
1101 Transmit ILAS on fourteenth LMFC after SYNCINB± deasserted.
1110 Transmit ILAS on fifteenth LMFC after SYNCINB± deasserted.
1111 Transmit ILAS on sixteenth LMFC after SYNCINB± deasserted.
3 Reserved Reserved. 0x0 R
[2:0] Link layer test mode 0x0 R/W
000 Normal operation (link layer test mode disabled).
001 Continuous sequence of /D21.5/ characters.
010 Reserved.
011 Reserved.
100 Modified RPAT test sequence.
101 JSPAT test sequence.
110 JTSPAT test sequence.
111 Reserved.
0x0578 JESD204B LMFC
offset
[7:5] Reserved Reserved. 0x0 R
[4:0] LMFC phase offset value Local multiframe clock (LMFC) phase offset value (in frame
clocks). Refer to the Deterministic Latency section.
0x0 R/W
0x0580 JESD204B DID
configuration
[7:0] JESD204B Tx DID value JESD204B serial device identification (DID) number. 0x0 R/W
0x0581 JESD204B BID
configuration
[7:4] Reserved Reserved. 0x0 R
[3:0] JESD204B Tx BID value JESD204B serial bank identification (BID) number (extension to
DID).
0x0 R/W
0x0583 JESD204B LID0
configuration
[7:5] Reserved Reserved. 0x0 R
[4:0] Lane 0 LID value JESD204B serial lane identification (LID) number for Lane 0. 0x0 R/W
0x0584 JESD204B LID1
configuration
[7:5] Reserved Reserved. 0x0 R
[4:0] Lane 1 LID value JESD204B serial lane identification (LID) number for Lane 1. 0x1 R/W
0x0585 JESD204B LID2
configuration
[7:5] Reserved Reserved. 0x0 R
[4:0] Lane 2 LID value JESD204B serial lane identification (LID) number for Lane 2. 0x2 R/W
0x0586 JESD204B LID3
configuration
[7:5] Reserved Reserved. 0x0 R
[4:0] Lane 3 LID value JESD204B serial lane identification (LID) number for Lane 3. 0x3 R/W
0x0587 JESD204B LID4
configuration
[7:5] Reserved Reserved. 0x0 R
[4:0] Lane 4 LID value JESD204B serial lane identification (LID) number for Lane 4. 0x4 R/W
0x0588 JESD204B LID5
configuration
[7:5] Reserved Reserved. 0x0 R
[4:0] Lane 5 LID value JESD204B serial lane identification (LID) number for Lane 5. 0x5 R/W
0x0589 JESD204B LID6
configuration
[7:5] Reserved Reserved. 0x0 R
[4:0] Lane 6 LID value JESD204B serial lane identification (LID) number for Lane 6. 0x6 R/W
0x058A JESD204B LID7
configuration
[7:5] Reserved Reserved. 0x0 R
[4:0] Lane 7 LID value JESD204B serial lane identification (LID) number for Lane 7. 0x7 R/W
Data Sheet AD9208
Rev. 0 | Page 117 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x058B JESD204B
scrambling and
number lanes (L)
configuration
7 JESD204B scrambling
(SCR)
0x1 R/W
0 JESD204B scrambler disabled (SCR = 0).
1 JESD204B scrambler enabled (SCR = 1).
[6:5] Reserved Reserved. 0x0 R
[4:0] JESD204B lanes (L) 0x7 R/W
0x0 One lane per link (L = 1).
0x1 Two lanes per link (L = 2).
0x3 Four lanes per link (L = 4).
0x7 Eight lanes per Link (L = 8).
0x058C JESD204B link
number of octets
per frames (F)
[7:0] JESD204B F configuration JESD204B number of octets per frame (F = JESD204B
F configuration + 1)
0x0 R/W
0 F = 1.
1 F = 2.
10 F = 3.
11 F = 4.
101 F = 6.
111 F = 8.
1111 F = 16.
0x058D JESD204B link
number of frames
per multiframe (K)
[7:5] Reserved Reserved. 0x0 R
[4:0] JESD204B K configuration JESD204B number of frames per multiframe (K = JESD204B K
configuration + 1). Only values where F × K is divisible by 4 can
be used.
0x1F R/W
0x058E JESD204B link
number of
converters (M)
[7:0] JESD204B M
configuration
JESD204B number of converters per link/device (M = JESD204B
M configuration).
0x1 R/W
0 Link connected to one virtual converter (M = 1).
1 Link connected to two virtual converters (M = 2).
11 Link connected to four virtual converters (M = 4).
111 Link connected to eight virtual converters (M = 8).
0x058F JESD204B number
of control bits (CS)
and ADC resolution
(N)
[7:6] Number of control bits
(CS) per sample
0x0 R/W
0 No control bits (CS = 0).
1 1 control bit (CS = 1), Control Bit 2 only.
10 2 control bits (CS = 2), Control Bit 2 and Control Bit 1 only.
11 3 control bits (CS = 3), all control bits (Control Bit 2, Control Bit 1,
and Control Bit 0).
5 Reserved Reserved. 0x0 R
[4:0] ADC converter resolution
(N)
0xF R/W
00110 N = 7-bit resolution.
00111 N = 8-bit resolution.
01000 N = 9-bit resolution.
01001 N = 10-bit resolution.
01010 N = 11-bit resolution.
01011 N = 12-bit resolution.
01100 N = 13-bit resolution.
01101 N = 14-bit resolution.
01110 N = 15-bit resolution.
01111 N = 16-bit resolution.
AD9208 Data Sheet
Rev. 0 | Page 118 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0590 JESD204B SCV NP
configuration
[7:5] Subclass support 0x1 R/W
000 Subclass 0.
001 Subclass 1.
[4:0] ADC number of bits per
sample(N')
0xF R/W
0 0111 N' = 8.
0 1011 N' = 12.
0 1111 N' = 16.
0x0591 JESD204B JV S
configuration
[7:5] Reserved Reserved. 0x1 R
[4:0] Samples per converter
frame cycle (S)
Samples per converter frame cycle (S = Register 0x0591,
Bits[4:0] + 1).
0x0 R
0x0592 JESD204B HD CF
configuration
7 HD value 0x0 R
0 High density format disabled.
1 High density format enabled.
[6:5] Reserved Reserved. 0x0 R
[4:0] Control words per frame
clock cycle per link (CF)
Number of control words per frame clock cycle per link
(CF = Register 0x0592, Bits[4:0]).
0x0 R
0x05A0 JESD204B
Checksum 0
configuration
[7:0] Checksum 0 checksum
value for SERDOUT0±
Serial checksum value for Lane 0. Automatically calculated for
each lane. Sum (all link configuration parameters for Lane 0)
mod 256.
0xC3 R
0x05A1 JESD204B
Checksum 1
configuration
[7:0] Checksum 1 checksum
value for SERDOUT1±
Serial checksum value for Lane 1. Automatically calculated for
each lane. Sum (all link configuration parameters for Lane 1)
mod 256.
0xC4 R
0x05A2 JESD204B
Checksum 2
configuration
[7:0] Checksum 2 checksum
value for SERDOUT2±
Serial checksum value for Lane 2. Automatically calculated for
each lane. Sum (all link configuration parameters for each lane)
mod 256.
0xC5 R
0x05A3 JESD204B
Checksum 3
configuration
[7:0] Checksum 3 checksum
value for SERDOUT3±
Serial checksum value for Lane 3. Automatically calculated for
each lane. Sum (all link configuration parameters for Lane 3)
mod 256.
0xC6 R
0x05B0 JESD204B lane
power-down
7 JESD204B Lane 7 power-
down
Physical Lane 7 force power-down. 0x0 R/W
0 SERDOUT7± normal operation.
1 SERDOUT7± power-down.
6 JESD204B Lane 6 power-
down
Physical Lane 6 force power-down. 0x0 R/W
0 SERDOUT6± normal operation.
1 SERDOUT6± power-down.
5 JESD204B Lane 5 power-
down
Physical Lane 5 force power-down. 0x0 R/W
0 SERDOUT5± normal operation.
1 SERDOUT5± power-down.
4 JESD204B Lane 4 power-
down
Physical Lane 4 force power-down. 0x0 R/W
0 SERDOUT4± normal operation.
1 SERDOUT4± power-down.
3 JESD204B Lane 3 power-
down
Physical Lane 3 force power-down. 0x0 R/W
0 SERDOUT3± normal operation.
1 SERDOUT3± power-down.
2 JESD204B Lane 2 power-
down
Physical Lane 2 force power-down. 0x0 R/W
0 SERDOUT2± normal operation.
1 SERDOUT2± power-down.
1 JESD204B Lane 1 power-
down
Physical Lane 1 force power-down. 0x0 R/W
0 SERDOUT1± normal operation.
1 SERDOUT1± power-down.
0 JESD204B Lane 0 power-
down
Physical Lane 0 force power-down. 0x0 R/W
0 SERDOUT0± normal operation.
1 SERDOUT0± power-down.
Data Sheet AD9208
Rev. 0 | Page 119 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x05B2 JESD204B Lane
Assign 1
7 Reserved Reserved. 0x0 R
[6:4] SERDOUT1± lane
assignment
Physical Lane 1 assignment. 0x1 R/W
0 Logical Lane 0.
1 Logical Lane 1 (default).
10 Logical Lane 2.
11 Logical Lane 3.
100 Logical Lane 4.
101 Logical Lane 5.
110 Logical Lane 6.
111 Logical Lane 7.
3 Reserved Reserved. 0x0 R
[2:0] SERDOUT0± lane
assignment
Physical Lane 0 assignment. 0x0 R/W
0 Logical Lane 0 (default).
1 Logical Lane 1.
10 Logical Lane 2.
11 Logical Lane 3.
100 Logical Lane 4.
101 Logical Lane 5.
110 Logical Lane 6.
111 Logical Lane 7.
0x05B3 JESD204B Lane
Assign 2
7 Reserved Reserved. 0x0 R
[6:4] SERDOUT3± lane
assignment
Physical Lane 3 assignment. 0x3 R/W
0 Logical Lane 0.
1 Logical Lane 1.
10 Logical Lane 2.
11 Logical Lane 3 (default).
100 Logical Lane 4.
101 Logical Lane 5.
110 Logical Lane 6.
111 Logical Lane 7.
3 Reserved Reserved. 0x0 R
[2:0] SERDOUT2± lane
assignment
Physical Lane 2 assignment. 0x2 R/W
0 Logical Lane 0.
1 Logical Lane 1
10 Logical Lane 2 (default).
11 Logical Lane 3.
100 Logical Lane 4.
101 Logical Lane 5.
110 Logical Lane 6.
111 Logical Lane 7.
0x05B5 JESD204B Lane
Assign 3
7 Reserved Reserved. 0x0 R
[6:4] SERDOUT5± lane
assignment
Physical Lane 5 assignment. 0x5 R/W
0 Logical Lane 0.
1 Logical Lane 1.
10 Logical Lane 2.
11 Logical Lane 3.
100 Logical Lane 4.
101 Logical Lane 5 (default).
110 Logical Lane 6.
111 Logical Lane 7.
3 Reserved Reserved. 0x0 R
AD9208 Data Sheet
Rev. 0 | Page 120 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
[2:0] SERDOUT4± lane
assignment
Physical Lane 4 assignment. 0x4 R/W
0 Logical Lane 0.
1 Logical Lane 1.
10 Logical Lane 2.
11 Logical Lane 3.
100 Logical Lane 4 (default).
101 Logical Lane 5.
110 Logical Lane 6.
111 Logical Lane 7.
0x05B6 JESD204B Lane
Assign 4
7 Reserved Reserved. 0x0 R
[6:4] SERDOUT7± lane
assignment
Physical Lane 7 assignment. 0x7 R/W
0 Logical Lane 0.
1 Logical Lane 1.
10 Logical Lane 2.
11 Logical Lane 3.
100 Logical Lane 4.
101 Logical Lane 5.
110 Logical Lane 6.
111 Logical Lane 7 (default).
3 Reserved Reserved. 0x0 R
[2:0] SERDOUT6± lane
assignment
Physical Lane 6 assignment. 0x6 R/W
0 Logical Lane 0.
1 Logical Lane 1.
10 Logical Lane 2.
11 Logical Lane 3.
100 Logical Lane 4.
101 Logical Lane 5.
110 Logical Lane 6 (default).
111 Logical Lane 7.
0x05BF SERDOUTx± data
invert
7 Invert SERDOUT7± data Invert SERDOUT7± data. 0x0 R/W
0 Normal.
1 Invert.
6 Invert SERDOUT6± data Invert SERDOUT6± data. 0x0 R/W
0 Normal.
1 Invert.
5 Invert SERDOUT5± data Invert SERDOUT5± data. 0x0 R/W
0 Normal.
1 Invert.
4 Invert SERDOUT4± data Invert SERDOUT4± data. 0x0 R/W
0 Normal.
1 Invert.
3 Invert SERDOUT3± data Invert SERDOUT3± data. 0x0 R/W
0 Normal.
1 Invert.
2 Invert SERDOUT2± data Invert SERDOUT2± data. 0x0 R/W
0 Normal.
1 Invert.
1 Invert SERDOUT1± data Invert SERDOUT1± data. 0x0 R/W
0 Normal.
1 Invert.
0 Invert SERDOUT0± data Invert SERDOUT0± data. 0x0 R/W
0 Normal.
1 Invert.
Data Sheet AD9208
Rev. 0 | Page 121 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x05C0 JESD204B Swing
Adjust 1
7 Reserved Reserved. 0x0 R
[6:4] SERDOUT1± voltage
swing adjust
Output swing level for SERDOUT1±. 0x1 R/W
000 1.0 × DRVDD1.
001 0.850 × DRVDD1.
010 0.750 × DRVDD1.
3 Reserved Reserved. 0x0 R
[2:0] SERDOUT0± voltage
swing adjust
Output swing level for SERDOUT0±. 0x1 R/W
000 1.0 × DRVDD1.
001 0.850 × DRVDD1.
010 0.750 × DRVDD1.
0x05C1 JESD204B Swing
Adjust 2
7 Reserved Reserved. 0x0 R
[6:4] SERDOUT3± voltage
swing adjust
Output swing level for SERDOUT3±. 0x1 R/W
000 1.0 × DRVDD1.
001 0.850 × DRVDD1.
010 0.750 × DRVDD1.
3 Reserved Reserved. 0x0 R
[2:0] SERDOUT2± voltage
swing adjust
Output swing level for SERDOUT2±. 0x1 R/W
000 1.0 × DRVDD1.
001 0.850 × DRVDD1.
010 0.750 × DRVDD1.
0x05C2 JESD204B Swing
Adjust 3
7 Reserved Reserved. 0x0 R
[6:4] SERDOUT5± voltage
swing adjust
Output swing level for SERDOUT5±. 0x1 R/W
000 1.0 × DRVDD1.
001 0.850 × DRVDD1.
010 0.750 × DRVDD1.
3 Reserved Reserved. 0x0 R
[2:0] SERDOUT4± voltage
swing adjust
Output swing level for SERDOUT4±. 0x1 R/W
000 1.0 × DRVDD1.
001 0.850 × DRVDD1.
010 0.750 × DRVDD1.
0x05C3 JESD204B Swing
Adjust 4
7 Reserved Reserved. 0x0 R
[6:4] SERDOUT7± voltage
swing adjust
Output swing level for SERDOUT7±. 0x1 R/W
000 1.0 × DRVDD1.
001 0.850 × DRVDD1.
010 0.750 × DRVDD1.
3 Reserved Reserved. 0x0 R
[2:0] SERDOUT6± voltage
swing adjust
Output swing level for SERDOUT6±. 0x1 R/W
000 1.0 × DRVDD1.
001 0.850 × DRVDD1.
010 0.750 × DRVDD1.
AD9208 Data Sheet
Rev. 0 | Page 122 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x05C4 SERDOUT0 pre-
emphasis select
7 Post tap enable Post tap enable. 0x0 R/W
0 Disable.
1 Enable.
[6:4] Set post tap level for
SERDOUT0±
Set post tap level. 0x0 R/W
000 0 dB.
001 3 dB.
010 6 dB.
011 9 dB.
100 12 dB.
[3:0] Reserved Reserved. 0x0 R/W
0x05C5 SERDOUT1 pre-
emphasis select
7 Post tap enable Post tap enable. 0x0 R/W
0 Disable.
1 Enable.
[6:4] Set post tap level for
SERDOUT1±
Set post tap level. 0x0 R/W
000 0 dB.
001 3 dB.
010 6 dB.
011 9 dB.
100 12 dB.
[3:0] Reserved Reserved. 0x0 R/W
0x05C6 SERDOUT2 pre-
emphasis select
7 Post tap enable Post tap enable. 0x0 R/W
0 Disable.
1 Enable.
[6:4] Set post tap level for
SERDOUT2±
Set post tap level. 0x0 R/W
000 0 dB.
001 3 dB.
010 6 dB.
011 9 dB.
100 12 dB.
[3:0] Reserved Reserved. 0x0 R/W
0x05C7 SERDOUT3 pre-
emphasis select
7 Post tap enable Post tap enable. 0x0 R/W
0 Disable.
1 Enable.
[6:4] Set post tap level for
SERDOUT3±
Set post tap level. 0x0 R/W
000 0 dB.
001 3 dB.
010 6 dB.
011 9 dB.
100 12 dB.
[3:0] Reserved Reserved. 0x0 R/W
0x05C8 SERDOUT4 pre-
emphasis select
7 Post tap enable Post tap enable. 0x0 R/W
0 Disable.
1 Enable.
[6:4] Set post tap level for
SERDOUT4±
Set post tap level. 0x0 R/W
000 0 dB.
001 3 dB.
010 6 dB.
011 9 dB.
100 12 dB.
[3:0] Reserved Reserved. 0x0 R/W
Data Sheet AD9208
Rev. 0 | Page 123 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x05C9 SERDOUT5 pre-
emphasis select
7 Post tap enable Post tap enable. 0x0 R/W
0 Disable.
1 Enable.
[6:4] Set post tap level for
SERDOUT5±
Set post tap level. 0x0 R/W
000 0 dB.
001 3 dB.
010 6 dB.
011 9 dB.
100 12 dB.
[3:0] Reserved Reserved. 0x0 R/W
0x05CA SERDOUT6 pre-
emphasis select
7 Post tap enable Post tap enable. 0x0 R/W
0 Disable.
1 Enable.
[6:4] Set post tap level for
SERDOUT6±
Set post tap level. 0x0 R/W
000 0 dB.
001 3 dB.
010 6 dB.
011 9 dB.
100 12 dB.
[3:0] Reserved Reserved. 0x0 R/W
0x05CB SERDOUT7 pre-
emphasis select
7 Post tap enable Post tap enable. 0x0 R/W
0 Disable
1 Enable
[6:4] Set post tap level for
SERDOUT7±
Set post tap level. 0x0 R/W
000 0 dB.
001 3 dB.
010 6 dB.
011 9 dB.
100 12 dB.
[3:0] Reserved Reserved. 0x0 R/W
0x1222 JESD204B PLL
calibration
[7:0] See Table 32. 0x00 R/W
0x00 JESD204B PLL Normal Operation
0x04 Reset JESD204B PLL calibration
0x1228 JESD204B PLL
start-up control
[7:0] See Table 32. 0x0F R/W
0x0F JESD204B start-up circuit in normal operation.
0x4F Reset JESD204B start-up circuit.
0x1262 JESD204B PLL LOL
bit control
[7:0] See Table 32. 0x00 R/W
0x00 Loss of lock bit normal operation.
0x80 Clear loss of lock bit.
AD9208 Data Sheet
Rev. 0 | Page 124 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
Programmable Filter Control and Coefficients Registers
0x0DF8 PFILT control [7:3] Reserved Reserved. 0x0 R
[2:0] PFILT mode Programmable filter (PFILT) mode. 0x0 R/W
000 = disabled (filters bypassed).
001 = single filter (X only).
DOUT_I[n] = DIN_I[n] * X_I[n].
DOUT_Q[n] = DIN_Q[n] * X_Q[n].
010 = single filter (X and Y together).
DOUT_I[n] = DIN_I[n] * XY_I[n].
DOUT_Q[n] = DIN_Q[n] * XY_Q[n].
100 = cascaded filters (X to Y).
DOUT_I[n] = DIN_I[n] * X_I[n] * Y_I[n].
DOUT_Q[n] = DIN_Q[n] * X_Q[n] * Y_Q[n].
DOUT_Q[n] = DIN_Q[n] * X_Q[n] * Y_Q[n].
101 = complex filters.
DOUT_I[n] = DIN_I[n] * X_I[n] + DIN_Q[n] * Y_Q[n].
DOUT_Q[n] = DIN_Q[n] * X_Q[n] + DIN_I[n] * Y_I[n].
110 = half complex filter.
DOUT_I[n] = DIN_I[n].
DOUT_Q[n] = DIN_Q[n] * XY_Q[n] + DIN_I[n] * XY_I[n].
111 = real 96-tap filter.
DOUT_I[n] = DIN_I[n] * XY_I[n].
DOUT_Q[n] = DIN_Q[n] * XY_Q[n].
0x0DF9 PFILT gain 7 Reserved Reserved. 0x0 R
[6:4] PFILT Y gain PFILT Y gain. 0x0 R/W
110 −12 dB loss.
111 −6 dB loss.
000 0 dB gain.
001 +6 dB gain.
010 +12 dB gain.
3 Reserved Reserved. 0x0 R
[2:0] PFILT X gain PFILT X gain. 0x0 R/W
110 −12 dB loss.
111 −6 dB loss.
000 0 dB gain.
001 +6 dB gain.
010 +12 dB gain.
0x0E00 PFILT X
Coefficient 0
[7:0] PFILT X Coefficient 0 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E01 PFILT X
Coefficient 1
[7:0] PFILT X Coefficient 1 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E02 PFILT X
Coefficient 2
[7:0] PFILT X Coefficient 2 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E03 PFILT X
Coefficient 3
[7:0] PFILT X Coefficient 3 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E04 PFILT X
Coefficient 4
[7:0] PFILT X Coefficient 4 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E05 PFILT X
Coefficient 5
[7:0] PFILT X Coefficient 5 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E06 PFILT X
Coefficient 6
[7:0] PFILT X Coefficient 6 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E07 PFILT X
Coefficient 7
[7:0] PFILT X Coefficient 7 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E08 PFILT X
Coefficient 8
[7:0] PFILT X Coefficient 8 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E09 PFILT X
Coefficient 9
[7:0] PFILT X Coefficient 9 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E0A PFILT X
Coefficient 10
[7:0] PFILT X Coefficient 10 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E0B PFILT X
Coefficient 11
[7:0] PFILT X Coefficient 11 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
Data Sheet AD9208
Rev. 0 | Page 125 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0E0C PFILT X
Coefficient 12
[7:0] PFILT X Coefficient 12 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E0D PFILT X
Coefficient 13
[7:0] PFILT X Coefficient 13 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E0E PFILT X
Coefficient 14
[7:0] PFILT X Coefficient 14 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E0F PFILT X
Coefficient 15
[7:0] PFILT X Coefficient 15 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E10 PFILT X
Coefficient 16
[7:0] PFILT X Coefficient 16 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E11 PFILT X
Coefficient 17
[7:0] PFILT X Coefficient 17 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E12 PFILT X
Coefficient 18
[7:0] PFILT X Coefficient 18 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E13 PFILT X
Coefficient 19
[7:0] PFILT X Coefficient 19 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E14 PFILT X
Coefficient 20
[7:0] PFILT X Coefficient 20 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E15 PFILT X
Coefficient 21
[7:0] PFILT X Coefficient 21 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E16 PFILT X
Coefficient 22
[7:0] PFILT X Coefficient 22 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E17 PFILT X
Coefficient 23
[7:0] PFILT X Coefficient 23 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E18 PFILT X
Coefficient 24
[7:0] PFILT X Coefficient 24 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E19 PFILT X
Coefficient 25
[7:0] PFILT X Coefficient 25 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E1A PFILT X
Coefficient 26
[7:0] PFILT X Coefficient 26 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E1B PFILT X
Coefficient 27
[7:0] PFILT X Coefficient 27 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E1C PFILT X
Coefficient 28
[7:0] PFILT X Coefficient 28 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E1D PFILT X
Coefficient 29
[7:0] PFILT X Coefficient 29 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E1E PFILT X
Coefficient 30
[7:0] PFILT X Coefficient 30 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E1F PFILT X
Coefficient 31
[7:0] PFILT X Coefficient 31 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E20 PFILT X
Coefficient 32
[7:0] PFILT X Coefficient 32 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E21 PFILT X
Coefficient 33
[7:0] PFILT X Coefficient 33 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E22 PFILT X
Coefficient 34
[7:0] PFILT X Coefficient 34 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E23 PFILT X
Coefficient 35
[7:0] PFILT X Coefficient 35 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E24 PFILT X
Coefficient 36
[7:0] PFILT X Coefficient 36 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E25 PFILT X
Coefficient 37
[7:0] PFILT X Coefficient 37 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E26 PFILT X
Coefficient 38
[7:0] PFILT X Coefficient 38 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E27 PFILT X
Coefficient 39
[7:0] PFILT X Coefficient 39 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E28 PFILT X
Coefficient 40
[7:0] PFILT X Coefficient 40 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E29 PFILT X
Coefficient 41
[7:0] PFILT X Coefficient 41 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E2A PFILT X
Coefficient 42
[7:0] PFILT X Coefficient 42 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E2B PFILT X
Coefficient 43
[7:0] PFILT X Coefficient 43 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
AD9208 Data Sheet
Rev. 0 | Page 126 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0E2C PFILT X
Coefficient 44
[7:0] PFILT X Coefficient 44 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E2D PFILT X
Coefficient 45
[7:0] PFILT X Coefficient 45 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E2E PFILT X
Coefficient 46
[7:0] PFILT X Coefficient 46 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E2F PFILT X
Coefficient 47
[7:0] PFILT X Coefficient 47 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E30 PFILT X
Coefficient 48
[7:0] PFILT X Coefficient 48 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E31 PFILT X
Coefficient 49
[7:0] PFILT X Coefficient 49 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E32 PFILT X
Coefficient 50
[7:0] PFILT X Coefficient 50 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E33 PFILT X
Coefficient 51
[7:0] PFILT X Coefficient 51 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E34 PFILT X
Coefficient 52
[7:0] PFILT X Coefficient 52 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E35 PFILT X
Coefficient 53
[7:0] PFILT X Coefficient 53 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E36 PFILT X
Coefficient 54
[7:0] PFILT X Coefficient 54 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E37 PFILT X
Coefficient 55
[7:0] PFILT X Coefficient 55 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E38 PFILT X
Coefficient 56
[7:0] PFILT X Coefficient 56 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E39 PFILT X
Coefficient 57
[7:0] PFILT X Coefficient 57 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E3A PFILT X
Coefficient 58
[7:0] PFILT X Coefficient 58 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E3B PFILT X
Coefficient 59
[7:0] PFILT X Coefficient 59 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E3C PFILT X
Coefficient 60
[7:0] PFILT X Coefficient 60 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E3D PFILT X
Coefficient 61
[7:0] PFILT X Coefficient 61 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E3E PFILT X
Coefficient 62
[7:0] PFILT X Coefficient 62 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E3F PFILT X
Coefficient 63
[7:0] PFILT X Coefficient 63 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E40 PFILT X
Coefficient 64
[7:0] PFILT X Coefficient 64 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E41 PFILT X
Coefficient 65
[7:0] PFILT X Coefficient 65 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E42 PFILT X
Coefficient 66
[7:0] PFILT X Coefficient 66 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E43 PFILT X
Coefficient 67
[7:0] PFILT X Coefficient 67 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E44 PFILT X
Coefficient 68
[7:0] PFILT X Coefficient 68 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E45 PFILT X
Coefficient 69
[7:0] PFILT X Coefficient 69 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E46 PFILT X
Coefficient 70
[7:0] PFILT X Coefficient 70 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E47 PFILT X
Coefficient 71
[7:0] PFILT X Coefficient 71 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E48 PFILT X
Coefficient 72
[7:0] PFILT X Coefficient 72 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E49 PFILT X
Coefficient 73
[7:0] PFILT X Coefficient 73 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E4A PFILT X
Coefficient 74
[7:0] PFILT X Coefficient 74 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E4B PFILT X
Coefficient 75
[7:0] PFILT X Coefficient 75 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
Data Sheet AD9208
Rev. 0 | Page 127 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0E4C PFILT X
Coefficient 76
[7:0] PFILT X Coefficient 76 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E4D PFILT X
Coefficient 77
[7:0] PFILT X Coefficient 77 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E4E PFILT X
Coefficient 78
[7:0] PFILT X Coefficient 78 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E4F PFILT X
Coefficient 79
[7:0] PFILT X Coefficient 79 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E50 PFILT X
Coefficient 80
[7:0] PFILT X Coefficient 80 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E51 PFILT X
Coefficient 81
[7:0] PFILT X Coefficient 81 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E52 PFILT X
Coefficient 82
[7:0] PFILT X Coefficient 82 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E53 PFILT X
Coefficient 83
[7:0] PFILT X Coefficient 83 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E54 PFILT X
Coefficient 84
[7:0] PFILT X Coefficient 84 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E55 PFILT X
Coefficient 85
[7:0] PFILT X Coefficient 85 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E56 PFILT X
Coefficient 86
[7:0] PFILT X Coefficient 86 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E57 PFILT X
Coefficient 87
[7:0] PFILT X Coefficient 87 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E58 PFILT X
Coefficient 88
[7:0] PFILT X Coefficient 88 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E59 PFILT X
Coefficient 89
[7:0] PFILT X Coefficient 89 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E5A PFILT X
Coefficient 90
[7:0] PFILT X Coefficient 90 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E5B PFILT X
Coefficient 91
[7:0] PFILT X Coefficient 91 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E5C PFILT X
Coefficient 92
[7:0] PFILT X Coefficient 92 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E5D PFILT X
Coefficient 93
[7:0] PFILT X Coefficient 93 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E5E PFILT X
Coefficient 94
[7:0] PFILT X Coefficient 94 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E5F PFILT X
Coefficient 95
[7:0] PFILT X Coefficient 95 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E60 PFILT X
Coefficient 96
[7:0] PFILT X Coefficient 96 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E61 PFILT X
Coefficient 97
[7:0] PFILT X Coefficient 97 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E62 PFILT X
Coefficient 98
[7:0] PFILT X Coefficient 98 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E63 PFILT X
Coefficient 99
[7:0] PFILT X Coefficient 99 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E64 PFILT X
Coefficient 100
[7:0] PFILT X Coefficient 100 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E65 PFILT X
Coefficient 101
[7:0] PFILT X Coefficient 101 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E66 PFILT X
Coefficient 102
[7:0] PFILT X Coefficient 102 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E67 PFILT X
Coefficient 103
[7:0] PFILT X Coefficient 103 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E68 PFILT X
Coefficient 104
[7:0] PFILT X Coefficient 104 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E69 PFILT X
Coefficient 105
[7:0] PFILT X Coefficient 105 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E6A PFILT X
Coefficient 106
[7:0] PFILT X Coefficient 106 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E6B PFILT X
Coefficient 107
[7:0] PFILT X Coefficient 107 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
AD9208 Data Sheet
Rev. 0 | Page 128 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0E6C PFILT X
Coefficient 108
[7:0] PFILT X Coefficient 108 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E6D PFILT X
Coefficient 109
[7:0] PFILT X Coefficient 109 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E6E PFILT X
Coefficient 110
[7:0] PFILT X Coefficient 110 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E6F PFILT X
Coefficient 111
[7:0] PFILT X Coefficient 111 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E70 PFILT X
Coefficient 112
[7:0] PFILT X Coefficient 112 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E71 PFILT X
Coefficient 113
[7:0] PFILT X Coefficient 113 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E72 PFILT X
Coefficient 114
[7:0] PFILT X Coefficient 114 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E73 PFILT X
Coefficient 115
[7:0] PFILT X Coefficient 115 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E74 PFILT X
Coefficient 116
[7:0] PFILT X Coefficient 116 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E75 PFILT X
Coefficient 117
[7:0] PFILT X Coefficient 117 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E76 PFILT X
Coefficient 118
[7:0] PFILT X Coefficient 118 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E77 PFILT X
Coefficient 119
[7:0] PFILT X Coefficient 119 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E78 PFILT X
Coefficient 120
[7:0] PFILT X Coefficient 120 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E79 PFILT X
Coefficient 121
[7:0] PFILT X Coefficient 121 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E7A PFILT X
Coefficient 122
[7:0] PFILT X Coefficient 122 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E7B PFILT X
Coefficient 123
[7:0] PFILT X Coefficient 123 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E7C PFILT X
Coefficient 124
[7:0] PFILT X Coefficient 124 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E7D PFILT X
Coefficient 125
[7:0] PFILT X Coefficient 125 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E7E PFILT X
Coefficient 126
[7:0] PFILT X Coefficient 126 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0E7F PFILT X
Coefficient 127
[7:0] PFILT X Coefficient 127 Programmable Filter X coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F00 PFILT Y
Coefficient 0
[7:0] PFILT Y Coefficient 0 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F01 PFILT Y
Coefficient 1
[7:0] PFILT Y Coefficient 1 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F02 PFILT Y
Coefficient 2
[7:0] PFILT Y Coefficient 2 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F03 PFILT Y
Coefficient 3
[7:0] PFILT Y Coefficient 3 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F04 PFILT Y
Coefficient 4
[7:0] PFILT Y Coefficient 4 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F05 PFILT Y
Coefficient 5
[7:0] PFILT Y Coefficient 5 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F06 PFILT Y
Coefficient 6
[7:0] PFILT Y Coefficient 6 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F07 PFILT Y
Coefficient 7
[7:0] PFILT Y Coefficient 7 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F08 PFILT Y
Coefficient 8
[7:0] PFILT Y Coefficient 8 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F09 PFILT Y
Coefficient 9
[7:0] PFILT Y Coefficient 9 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F0A PFILT Y
Coefficient 10
[7:0] PFILT Y Coefficient 10 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F0B PFILT Y
Coefficient 11
[7:0] PFILT Y Coefficient 11 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
Data Sheet AD9208
Rev. 0 | Page 129 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0F0C PFILT Y
Coefficient 12
[7:0] PFILT Y Coefficient 12 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F0D PFILT Y
Coefficient 13
[7:0] PFILT Y Coefficient 13 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F0E PFILT Y
Coefficient 14
[7:0] PFILT Y Coefficient 14 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F0F PFILT Y
Coefficient 15
[7:0] PFILT Y Coefficient 15 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F10 PFILT Y
Coefficient 16
[7:0] PFILT Y Coefficient 16 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F11 PFILT Y
Coefficient 17
[7:0] PFILT Y Coefficient 17 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F12 PFILT Y
Coefficient 18
[7:0] PFILT Y Coefficient 18 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F13 PFILT Y
Coefficient 19
[7:0] PFILT Y Coefficient 19 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F14 PFILT Y
Coefficient 20
[7:0] PFILT Y Coefficient 20 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F15 PFILT Y
Coefficient 21
[7:0] PFILT Y Coefficient 21 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F16 PFILT Y
Coefficient 22
[7:0] PFILT Y Coefficient 22 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F17 PFILT Y
Coefficient 23
[7:0] PFILT Y Coefficient 23 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F18 PFILT Y
Coefficient 24
[7:0] PFILT Y Coefficient 24 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F19 PFILT Y
Coefficient 25
[7:0] PFILT Y Coefficient 25 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F1A PFILT Y
Coefficient 26
[7:0] PFILT Y Coefficient 26 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F1B PFILT Y
Coefficient 27
[7:0] PFILT Y Coefficient 27 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F1C PFILT Y
Coefficient 28
[7:0] PFILT Y Coefficient 28 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F1D PFILT Y
Coefficient 29
[7:0] PFILT Y Coefficient 29 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F1E PFILT Y
Coefficient 30
[7:0] PFILT Y Coefficient 30 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F1F PFILT Y
Coefficient 31
[7:0] PFILT Y Coefficient 31 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F20 PFILT Y
Coefficient 32
[7:0] PFILT Y Coefficient 32 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F21 PFILT Y
Coefficient 33
[7:0] PFILT Y Coefficient 33 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F22 PFILT Y
Coefficient 34
[7:0] PFILT Y Coefficient 34 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F23 PFILT Y
Coefficient 35
[7:0] PFILT Y Coefficient 35 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F24 PFILT Y
Coefficient 36
[7:0] PFILT Y Coefficient 36 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F25 PFILT Y
Coefficient 37
[7:0] PFILT Y Coefficient 37 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F26 PFILT Y
Coefficient 38
[7:0] PFILT Y Coefficient 38 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F27 PFILT Y
Coefficient 39
[7:0] PFILT Y Coefficient 39 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F28 PFILT Y
Coefficient 40
[7:0] PFILT Y Coefficient 40 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F29 PFILT Y
Coefficient 41
[7:0] PFILT Y Coefficient 41 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F2A PFILT Y
Coefficient 42
[7:0] PFILT Y Coefficient 42 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F2B PFILT Y
Coefficient 43
[7:0] PFILT Y Coefficient 43 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
AD9208 Data Sheet
Rev. 0 | Page 130 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0F2C PFILT Y
Coefficient 44
[7:0] PFILT Y Coefficient 44 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F2D PFILT Y
Coefficient 45
[7:0] PFILT Y Coefficient 45 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F2E PFILT Y
Coefficient 46
[7:0] PFILT Y Coefficient 46 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F2F PFILT Y
Coefficient 47
[7:0] PFILT Y Coefficient 47 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F30 PFILT Y
Coefficient 48
[7:0] PFILT Y Coefficient 48 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F31 PFILT Y
Coefficient 49
[7:0] PFILT Y Coefficient 49 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F32 PFILT Y
Coefficient 50
[7:0] PFILT Y Coefficient 50 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F33 PFILT Y
Coefficient 51
[7:0] PFILT Y Coefficient 51 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F34 PFILT Y
Coefficient 52
[7:0] PFILT Y Coefficient 52 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F35 PFILT Y
Coefficient 53
[7:0] PFILT Y Coefficient 53 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F36 PFILT Y
Coefficient 54
[7:0] PFILT Y Coefficient 54 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F37 PFILT Y
Coefficient 55
[7:0] PFILT Y Coefficient 55 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F38 PFILT Y
Coefficient 56
[7:0] PFILT Y Coefficient 56 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F39 PFILT Y
Coefficient 57
[7:0] PFILT Y Coefficient 57 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F3A PFILT Y
Coefficient 58
[7:0] PFILT Y Coefficient 58 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F3B PFILT Y
Coefficient 59
[7:0] PFILT Y Coefficient 59 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F3C PFILT Y
Coefficient 60
[7:0] PFILT Y Coefficient 60 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F3D PFILT Y
Coefficient 61
[7:0] PFILT Y Coefficient 61 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F3E PFILT Y
Coefficient 62
[7:0] PFILT Y Coefficient 62 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F3F PFILT Y
Coefficient 63
[7:0] PFILT Y Coefficient 63 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F40 PFILT Y
Coefficient 64
[7:0] PFILT Y Coefficient 64 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F41 PFILT Y
Coefficient 65
[7:0] PFILT Y Coefficient 65 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F42 PFILT Y
Coefficient 66
[7:0] PFILT Y Coefficient 66 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F43 PFILT Y
Coefficient 67
[7:0] PFILT Y Coefficient 67 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F44 PFILT Y
Coefficient 68
[7:0] PFILT Y Coefficient 68 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F45 PFILT Y
Coefficient 69
[7:0] PFILT Y Coefficient 69 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F46 PFILT Y
Coefficient 70
[7:0] PFILT Y Coefficient 70 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F47 PFILT Y
Coefficient 71
[7:0] PFILT Y Coefficient 71 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F48 PFILT Y
Coefficient 72
[7:0] PFILT Y Coefficient 72 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F49 PFILT Y
Coefficient 73
[7:0] PFILT Y Coefficient 73 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F4A PFILT Y
Coefficient 74
[7:0] PFILT Y Coefficient 74 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F4B PFILT Y
Coefficient 75
[7:0] PFILT Y Coefficient 75 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
Data Sheet AD9208
Rev. 0 | Page 131 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0F4C PFILT Y
Coefficient 76
[7:0] PFILT Y Coefficient 76 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F4D PFILT Y
Coefficient 77
[7:0] PFILT Y Coefficient 77 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F4E PFILT Y
Coefficient 78
[7:0] PFILT Y Coefficient 78 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F4F PFILT Y
Coefficient 79
[7:0] PFILT Y Coefficient 79 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F50 PFILT Y
Coefficient 80
[7:0] PFILT Y Coefficient 80 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F51 PFILT Y
Coefficient 81
[7:0] PFILT Y Coefficient 81 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F52 PFILT Y
Coefficient 82
[7:0] PFILT Y Coefficient 82 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F53 PFILT Y
Coefficient 83
[7:0] PFILT Y Coefficient 83 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F54 PFILT Y
Coefficient 84
[7:0] PFILT Y Coefficient 84 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F55 PFILT Y
Coefficient 85
[7:0] PFILT Y Coefficient 85 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F56 PFILT Y
Coefficient 86
[7:0] PFILT Y Coefficient 86 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F57 PFILT Y
Coefficient 87
[7:0] PFILT Y Coefficient 87 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F58 PFILT Y
Coefficient 88
[7:0] PFILT Y Coefficient 88 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F59 PFILT Y
Coefficient 89
[7:0] PFILT Y Coefficient 89 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F5A PFILT Y
Coefficient 90
[7:0] PFILT Y Coefficient 90 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F5B PFILT Y
Coefficient 91
[7:0] PFILT Y Coefficient 91 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F5C PFILT Y
Coefficient 92
[7:0] PFILT Y Coefficient 92 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F5D PFILT Y
Coefficient 93
[7:0] PFILT Y Coefficient 93 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F5E PFILT Y
Coefficient 94
[7:0] PFILT Y Coefficient 94 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F5F PFILT Y
Coefficient 95
[7:0] PFILT Y Coefficient 95 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F60 PFILT Y
Coefficient 96
[7:0] PFILT Y Coefficient 96 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F61 PFILT Y
Coefficient 97
[7:0] PFILT Y Coefficient 97 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F62 PFILT Y
Coefficient 98
[7:0] PFILT Y Coefficient 98 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F63 PFILT Y
Coefficient 99
[7:0] PFILT Y Coefficient 99 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F64 PFILT Y
Coefficient 100
[7:0] PFILT Y Coefficient 100 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F65 PFILT Y
Coefficient 101
[7:0] PFILT Y Coefficient 101 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F66 PFILT Y
Coefficient 102
[7:0] PFILT Y Coefficient 102 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F67 PFILT Y
Coefficient 103
[7:0] PFILT Y Coefficient 103 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F68 PFILT Y
Coefficient 104
[7:0] PFILT Y Coefficient 104 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F69 PFILT Y
Coefficient 105
[7:0] PFILT Y Coefficient 105 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F6A PFILT Y
Coefficient 106
[7:0] PFILT Y Coefficient 106 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F6B PFILT Y
Coefficient 107
[7:0] PFILT Y Coefficient 107 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
AD9208 Data Sheet
Rev. 0 | Page 132 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x0F6C PFILT Y
Coefficient 108
[7:0] PFILT Y Coefficient 108 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F6D PFILT Y
Coefficient 109
[7:0] PFILT Y Coefficient 109 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F6E PFILT Y
Coefficient 110
[7:0] PFILT Y Coefficient 110 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F6F PFILT Y
Coefficient 111
[7:0] PFILT Y Coefficient 111 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F70 PFILT Y
Coefficient 112
[7:0] PFILT Y Coefficient 112 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F71 PFILT Y
Coefficient 113
[7:0] PFILT Y Coefficient 113 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F72 PFILT Y
Coefficient 114
[7:0] PFILT Y Coefficient 114 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F73 PFILT Y
Coefficient 115
[7:0] PFILT Y Coefficient 115 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F74 PFILT Y
Coefficient 116
[7:0] PFILT Y Coefficient 116 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F75 PFILT Y
Coefficient 117
[7:0] PFILT Y Coefficient 117 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F76 PFILT Y
Coefficient 118
[7:0] PFILT Y Coefficient 118 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F77 PFILT Y
Coefficient 119
[7:0] PFILT Y Coefficient 119 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F78 PFILT Y
Coefficient 120
[7:0] PFILT Y Coefficient 120 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F79 PFILT Y
Coefficient 121
[7:0] PFILT Y Coefficient 121 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F7A PFILT Y
Coefficient 122
[7:0] PFILT Y Coefficient 122 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F7B PFILT Y
Coefficient 123
[7:0] PFILT Y Coefficient 123 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F7C PFILT Y
Coefficient 124
[7:0] PFILT Y Coefficient 124 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F7D PFILT Y
Coefficient 125
[7:0] PFILT Y Coefficient 125 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F7E PFILT Y
Coefficient 126
[7:0] PFILT Y Coefficient 126 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
0x0F7F PFILT Y
Coefficient 127
[7:0] PFILT Y Coefficient 127 Programmable Filter Y coefficients. Coefficients are only
applied after the chip transfer bit is written.
0x0 R/W
VREF/Analog Input Control Registers
0x0701 DC offset calibration
control (local)
[7:0] DC offset calibration
control
0x06 R/W
0x06 Disable.
0x86 Enable.
0x18A6 VREF control [7:1] Reserved Reserved. 0x0 R
0 VREF control 0x0 R/W
0 Internal reference.
1 External reference.
0x18E3 External VCM
buffer control
7 Reserved Reserved. 0x0 R
6 External VCM buffer 0x0 R/W
0 Disable.
1 Enable.
[5:0] External VCM buffer [5:0] See the Input Common Mode section. 0x0 R/W
Data Sheet AD9208
Rev. 0 | Page 133 of 136
Addr. Name Bits Bit Name Settings Description Reset Access
0x18E6 Temperature diode
export
[7:0] Temperature diode
location select
See the Temperature Diode section. 0x0 R/W
0x00 Central diode. VREF pin = high-Z.
0x01 Central diode. VREF pin = 1× diode voltage output.
0x02 Central diode. VREF pin = 20× diode voltage output.
0x03 Central diode. VREF pin = GND.
0x40 Channel A diode. VREF pin = high-Z.
0x41 Channel A diode. VREF pin = 1× diode voltage output.
0x42 Channel A diode. VREF pin = 20× diode voltage output.
0x43 Channel A diode. VREF pin = GND.
0x50 Channel B diode. VREF pin = high-Z.
0x51 Channel B diode. VREF pin = 1× diode voltage output.
0x52 Channel B diode. VREF pin = 20× diode voltage output.
0x53 Channel B diode. VREF pin = GND.
0x1908 Analog input
control (local)
[7:3] Reserved Reserved. 0x0 R
2 Enable dc coupling 0x0 R/W
0 Analog input is optimized for ac coupling.
1 Analog input is optimized for dc coupling.
[1:0] Reserved Reserved. 0x0 R
0x1910 Input full-scale
control (local)
[7:4] Reserved Reserved. 0x0 R
[3:0] Input full-scale voltage Full-scale voltage setting. 0xD R/W
1000 1.13 V p-p differential.
1001 1.25 V p-p differential.
1101 1.7 V p-p differential.
1110 1.81 V p-p differential.
1111 1.93 V p-p differential.
0000 2.04 V p-p differential.
0x1A4C Buffer Control 1
(local)
[7:6] Reserved Reserved. 0x0 R
[5:0] Buffer Control 1 Input Buffer Main Current 1. See the Analog Input Buffer
Controls and SFDR Optimization section.
0x19 R/W
00 0100 Buffer current set to 400 µA.
00 1001 Buffer current set to 500 µA.
01 1110 Buffer current set to 600 µA.
10 0011 Buffer current set to 700 µA.
10 1000 Buffer current set to 800 µA.
11 0010 Buffer current set to 1000 µA.
0x1A4D Buffer Control 2
(local)
[7:6] Reserved Reserved. 0x0 R
[5:0] Buffer Control 2 Input Buffer Main Current 2. See the Analog Input Buffer
Controls and SFDR Optimization section.
0x19 R/W
00 0100 Buffer current set to 400 µA.
00 1001 Buffer current set to 500 µA.
01 1110 Buffer current set to 600 µA.
10 0011 Buffer current set to 700 µA.
10 1000 Buffer current set to 800 µA.
11 0010 Buffer current set to 1000 µA.
AD9208 Data Sheet
Rev. 0 | Page 134 of 136
APPLICATIONS INFORMATION
POWER SUPPLY RECOMMENDATIONS
The power supplies needed to power the AD9208 are shown in
Table 47. A power-on sequence is not required to operate the
AD9208. The power supply domains can be powered up in any
order.
Table 47. Typical Power Supplies for the AD9208
Domain Voltage (V) Tolerance (%)
AVDD1 0.975 ±2.5
AVDD1_SR 0.975 ±2.5
DVDD 0.975 ±2.5
DRVDD1 0.975 ±2.5
AVDD2 1.9 ±2.5
DRVDD2 1.9 ±2.5
SPIVDD 1.9 ±2.5
AVDD3 2.5 ±2.5
For applications requiring an optimal high power efficiency and
low noise performance, it is recommended that the ADP5054
quad switching regulator be used to convert an input voltage in
the 6.0 V to 15 V range to intermediate rails (1.3 V, 2.4 V, and
3.0 V). These intermediate rails are then postregulated by very
low noise, low dropout (LDO) regulators (ADP1763, ADP7159,
and ADP151). Figure 131 shows the recommended power
supply scheme for the AD9208.
AVDD1
0.975V
1.3
V
ANALOG
AVDD1_SR
0.975V
DVDD
0.975V
DRVDD1
0.975V
AVDD2
1.9V
DRVDD2
1.9V
ADP5054
6.0V
TO
15.0V
AVDD3
2.5V
3.0V
LDO
SWITCHER
OPTIONAL PATH
1.3V
DIGITAL
OPTIONAL
2.4V
SPIVDD
1.9V
REFERENCED TO AGND
OPTIONAL
ADP1763
ADP1763
ADP7159
ADP151
ADP7159
15547-126
Figure 131. High Efficiency, Low Noise Power Solution for the AD9208
It is not necessary to split all of these power domains in all cases.
The recommended solution shown in Figure 131 provides the
lowest noise, highest efficiency power delivery system for the
AD9208. If only one 0.975 V supply is available, route to AVDD1
first and then tap it off and isolate it with a ferrite bead or a
filter choke, preceded by decoupling capacitors for AVDD1_SR,
DVDD, and DRVDD1, in that order. Figure 132 shows the
simplified schematic. The dc resistance (DCR) of the ferrite
bead must be taken into consideration when choosing the
appropriate ferrite bead. Otherwise, excessive loss across the
ferrite bead can lead to a malfunctioning ADC. Adjustable LDOs
can be employed to output a higher voltage to account for the
drop across the ferrite bead.
Alternatively, the LDOs can be bypassed altogether and the
AD9208 can be driven directly from the dc-to-dc converter.
Note that this approach has risks in that there may be more
power supply noise injected into the power supply domains of
the ADC. To minimize noise, follow the layout guidelines of the
dc-to-dc converter.
AVDD1
0.975V
1.3V
ANALOG
AVDD1_SR
0.975V
DVDD
0.975V
DRVDD1
0.975V
AVDD2
1.9V
DRVDD2
1.9V
ADP5054
12V FROM FMC OR
6.0V FROM WALL
SUPPLY
AVDD3
2.5V
3.0V
LDO
SWITCHER
OPTIONAL PATH
FERRITE BEAD
1.3V
DIGITAL
2.4V
SW3
SW4
SW1
SW2
ADP1763
ADP7159
ADP7159
SPIVDD
1.9V
NOTES
1. ALL VOLTAGES REFERENCED TO AGND.
15547-127
Figure 132. Simplified Power Solution for the AD9208
The user can employ several different decoupling capacitors to
cover both high and low frequencies. These capacitors must be
located close to the point of entry at the PCB level and close to
the devices, with minimal trace lengths.
Data Sheet AD9208
Rev. 0 | Page 135 of 136
LAYOUT GUIDELINES
The ADC evaluation board can be used as a guide to follow
good layout practices. The evaluation board layout is set up in
such a way as to
Minimize coupling between the analog inputs (Channel A
to Channel B and Channel B to Channel A).
Minimize clock coupling to the analog inputs.
Provide enough power and ground planes for the various
supply domains while reducing cross coupling.
Provide adequate thermal relief to the ADC.
Figure 133 shows the overall layout scheme used for the
AD9208 evaluation board.
AVDD1_SR (PIN E7) AND AGND (PIN E6 AND PIN E8)
AVDD1_SR (Pin E7) and AGND (Pin E6 and Pin E8) can be
used to provide a separate power supply node to the SYSREF±
circuits of the AD9208. If running in Subclass 1, the AD9208
can support periodic one-shot or gapped signals. To minimize
the coupling of this supply into the AVDD1 supply node,
adequate supply bypassing is needed.
ADC
CH.A
CH.B
CLK JESD204B LANES
POWER
SYSREF
15547-128
Figure 133. Recommended PCB Layout for the AD9208
AD9208 Data Sheet
Rev. 0 | Page 136 of 136
OUTLINE DIMENSIONS
COMPLIANT TO JEDEC STANDARDS MO-275-GGAB-1.
12-07-2015-B
0.80
0.80 REF
0.34 REF
0.71
REF
A
B
C
D
E
F
G
0191141312113246578
BOTTOM VIEW
10.40 REF
SQ
H
J
K
L
M
N
P
TOP VIEW
COPLANARITY
0.12
0.50
0.45
0.40
BALL DIAMETER
SEATING
PLANE
12.10
12.00 SQ
11.90
A1 BALL
PAD CORNER
A1 BALL
PAD CORNER
1.53
1.42
1.31
11.20 SQ
7.50 SQ
1.19
1.09
0.99
0.38
0.33
0.28
PKG-004807
DETAIL A
SIDE VIEW
DETAIL A
Figure 134. 196-Ball Ball Grid Array, Thermally Enhanced [BGA_ED]
12 mm × 12 mm (BP-196-4)
Dimensions shown in millimeters
ORDERING GUIDE
Model1 Temperature Range Package Description Package Option
AD9208BBPZ-3000 −40°C to +85°C 196-Ball Ball Grid Array, Thermally Enhanced [BGA_ED] BP-196-4
AD9208BBPZRL-3000 −40°C to +85°C 196-Ball Ball Grid Array, Thermally Enhanced [BGA_ED] BP-196-4
AD9208-3000EBZ Evaluation Board
1 Z = RoHS Compliant Part.
©2017 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D15547-0-4/17(0)
