14-Bit, 2.0 GSPS/2.6 GSPS, JESD204B,
Dual Analog-to-Digital Converter
Data Sheet AD9689
Rev. A Document Feedback
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FEATURES
JESD204B (Subclass 1) coded serial digital outputs
Support for lane rates up to 16 Gbps per lane
Noise density
−152 dBFS/Hz at 2.56 GSPS at full-scale voltage = 1.7 V p-p
−154 dBFS/Hz at 2.56 GSPS at full-scale voltage = 2.0 V p-p
−154.2 dBFS/Hz at 2.0 GSPS at full-scale voltage = 1.7 V p-p
−155.3 dBFS/Hz at 2.0 GSPS at full-scale voltage = 2.0 V p-p
1.55 W total power per channel at 2.56 GSPS (default settings)
SFDR at 2.56 GSPS encode
73 dBFS at 1.8 GHz AIN at −2.0 dBFS
59 dBFS at 5.53 GHz AIN at −2.0 dBFS
full-scale voltage = 1.1 V p-p
SNR at 2.56 GSPS encode
59.7 dBFS at 1.8 GHz AIN at −2.0 dBFS
53.0 dBFS at 5.53 GHz AIN at −2.0 dBFS
full-scale voltage = 1.1 V p-p
SFDR at 2.0 GSPS encode
78 dBFS at 900 MHz AIN at −2.0 dBFS
62 dBFS at 5.53 GHz AIN at −2.0 dBFS
full-scale voltage = 1.1 V p-p
SNR at 2.0 GSPS encode
62.7 dBFS at 900 MHz AIN at −2.0 dBFS
53.1 dBFS at 5.5 GHz AIN at −2.0 dBFS
full-scale voltage = 1.1 V p-p
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
Programmable FIR filters for analog channel loss equalization
2 integrated, wideband digital processors per channel
48-bit NCO
Programmable decimation rates
Phase coherent NCO switching
Up to 4 channels available
Serial port control
Supports 100 MHz SPI writes and 50 MHz SPI reads
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_SR
(0.975V)
SPI AND
CONTROL
REGISTERS
SDIO SCLK CSB
VIN–B
BUFFER
ADC
CORE
÷2
÷4
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
15550-001
AD9689
Figure 1.
AD9689* PRODUCT PAGE QUICK LINKS
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EVALUATION KITS
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Data Sheet
•AD9689: 14-Bit, 2.0 GSPS/2.6 GSPS, JESD204B, Dual
Analog-to-Digital Converter Data Sheet
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•AD9689 S-Parameters
REFERENCE MATERIALS
Press
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Converter
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•AD9689 Material Declaration
•PCN-PDN Information
•Quality And Reliability
•Symbols and Footprints
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AD9689 Data Sheet
Rev. A | Page 2 of 134
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 3
General Description ......................................................................... 4
Product Highlights ........................................................................... 4
Specifications ..................................................................................... 5
DC Specifications ......................................................................... 5
AC Specifications .......................................................................... 6
Digital Specifications ................................................................... 8
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
2.0 GSPS ....................................................................................... 16
2.6 GSPS ....................................................................................... 21
Equivalent Circuits ......................................................................... 26
Theory of Operation ...................................................................... 28
ADC Architecture ...................................................................... 28
Analog Input Considerations .................................................... 28
Voltage Reference ....................................................................... 31
DC Offset Calibration ................................................................ 32
Clock Input Considerations ...................................................... 32
Power-Down and Standby Mode ............................................. 35
Temperature Diode .................................................................... 35
ADC Overrange and Fast Detect .................................................. 37
ADC Overrange .......................................................................... 37
Fast Threshold Detection (FD_A and FD_B) ........................ 37
ADC Application Modes and JESD204B Tx Converter Mapping
........................................................................................................... 38
Programmable FIR Filters ............................................................. 40
Supported Modes........................................................................ 40
Programming Instructions ........................................................ 42
Digital Downconverter (DDC) ..................................................... 44
DDC I/Q Input Selection .......................................................... 44
DDC I/Q Output Selection ....................................................... 44
DDC General Description ........................................................ 44
DDC Frequency Translation ..................................................... 47
DDC Decimation Filters ........................................................... 55
DDC Gain Stage ......................................................................... 61
DDC Complex to Real Conversion ......................................... 61
DDC Mixed Decimation Settings ............................................ 62
DDC Example Configurations ................................................. 64
DDC Power Consumption ........................................................ 67
Signal Monitor ................................................................................ 68
SPORT over JESD204B .............................................................. 69
Digital Outputs ............................................................................... 71
Introduction to the JESD204B Interface ................................. 71
JESD204B Overview .................................................................. 71
Functional Overview ................................................................. 72
JESD204B Link Establishment ................................................. 72
Physical Layer (Driver) Outputs .............................................. 74
fS × 4 Mode .................................................................................. 75
Setting Up the AD9689 Digital Interface ................................. 76
Deterministic Latency .................................................................... 83
Subclass 0 Operation .................................................................. 83
Subclass 1 Operation .................................................................. 83
Multichip Synchronization ............................................................ 85
Normal Mode .............................................................................. 85
Timestamp Mode ....................................................................... 85
SYSREF Input .............................................................................. 87
SYSREF± Setup/Hold Window Monitor ................................. 89
Latency ............................................................................................. 91
End to End Total Latency .......................................................... 91
Example Latency Calculations.................................................. 91
LMFC Referenced Latency ........................................................ 91
Test Modes ....................................................................................... 93
ADC Test Modes ........................................................................ 93
JESD204B Block Test Modes .................................................... 94
Serial Port Interface ........................................................................ 96
Configuration Using the SPI ..................................................... 96
Hardware Interface ..................................................................... 96
SPI Accessible Features .............................................................. 96
Memory Map .................................................................................. 97
Reading the Memory Map Register Table ............................... 97
Memory Map Register Details .................................................. 98
Applications Information ............................................................ 132
Data Sheet AD9689
Rev. A | Page 3 of 134
Power Supply Recommendations .......................................... 132
Layout Guidelines .................................................................... 133
AVDD1_SR (Pin E7) and AGND (Pin E6 and Pin E8) ........... 133
Outline Dimensions ...................................................................... 134
Ordering Guide ......................................................................... 134
REVISION HISTORY
10/2017—Rev. 0 to Rev. A
Added 2.0 GSPS ............................................................. Throughout
Changes to Features Section ............................................................ 1
Changes to Product Highlights Section ......................................... 4
Changes to Table 1 ............................................................................ 5
Changes to Table 2 ............................................................................ 6
Changes to Table 4 ............................................................................ 9
Added 2.0 GSPS Section and Figure 6 to Figure 11; Renumbered
Sequentially ...................................................................................... 16
Added Figure 12 to Figure 17 ........................................................ 17
Added Figure 18 to Figure 23 ........................................................ 18
Added Figure 24 through Figure 29 .............................................. 19
Added Figure 30 through Figure 35 .............................................. 20
Added 2.6 GSPS Section ................................................................. 21
Change to Figure 41 ........................................................................ 21
Change to Figure 45 ........................................................................ 22
Changes to Figure 52 and Figure 53 ............................................. 23
Changes to Figure 54, Figure 55, Figure 56, Figure 58, and
Figure 59 ........................................................................................... 24
Changes to Figure 60 and Figure 61 ............................................. 25
Changes to Figure 67 Caption ....................................................... 26
Changes to Table 10 ........................................................................ 30
Changes to Figure 87 ...................................................................... 32
Changes to Figure 96 Caption ....................................................... 35
Changes to Programming Instructions Section .......................... 42
Added Table 28; Renumbered Sequentially ................................. 67
Changes to Table 29 Title ............................................................... 67
Changes to De-Emphasis Section ................................................. 74
Changes to Figure 142 .................................................................... 82
Changes to Reading the Memory Map Register Table Section ....... 97
Changes to Address 0x0006, Table 46 .......................................... 98
Changes to Address 0x010A, Table 47 ......................................... 99
Changes to Table 50 ...................................................................... 105
Changes to Table 51 ...................................................................... 117
Changes to Power Supply Recommendations Section, Figure 157,
and Figure 158 ............................................................................... 132
Changes to Ordering Guide ......................................................... 134
9/2017—Revision 0: Initial Version
AD9689 Data Sheet
Rev. A | Page 4 of 134
GENERAL DESCRIPTION
The AD9689 is a dual, 14-bit, 2.0 GSPS/2.6 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 AD9689 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 multiple cascaded signal
processing stages: a 48-bit frequency translator (numerically
controlled oscillator (NCO)), and decimation rates. 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 AD9689 between the DDC modes is
selectable via SPI-programmable profiles.
In addition to the DDC blocks, the AD9689 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 AD9689 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 AD9689 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 AD9689 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 filters and NCO
blocks supporting multiband receivers.
3. Fast NCO switching enabled through the GPIO pins.
4. 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.
8. Pin, package, feature, and memory map compatible with
the AD9208 14-bit, 3.0 GSPS, JESD204B dual ADC.
Data Sheet AD9689
Rev. A | Page 5 of 134
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, sampling rate = 2.0 GHz/2.56 GHz, clock divider = 2, 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.
2.0 GSPS 2.6 GSPS
Parameter Min Typ Max Min Typ Max Unit
RESOLUTION 14 14 Bits
ACCURACY
No Missing Codes Guaranteed Guaranteed
Offset Error 0 %FSR
Offset Matching
0
0
%FSR
Gain Error −2.9 ±1 +1.8 −4.9 ±1 +5.6 %FSR
Gain Matching ±0.2 ±0.2 %FSR
Differential Nonlinearity (DNL) −0.62 ±0.4 +0.79 −0.65 ±0.4 +0.75 LSB
Integral Nonlinearity (INL) −9.9 ±2 +8.1 −16 ±6 +13 LSB
TEMPERATURE DRIFT
Offset Error ±7.7 ±3.7 ppm/°C
Gain Error 15 58 ppm/°C
INTERNAL VOLTAGE REFERENCE 0.5 0.5 V
INPUT REFERRED NOISE 3.8 4.6 LSB rms
ANALOG INPUTS
Differential Input Voltage Range 1.1 1.7 2.0 1.1 1.7 2.0 V p-p
Common-Mode Voltage (VCM) 1.4 1.4 V
Differential Input Capacitance 0.35 0.35 pF
−3 dB Bandwidth 9 9 GHz
POWER SUPPLY
AVDD1 0.95 0.975 1.0 0.95 0.975 1.0 V
AVDD2 1.85 1.9 1.95 1.85 1.9 1.95 V
AVDD3 2.44 2.5 2.56 2.44 2.5 2.56 V
AVDD1_SR 0.95 0.975 1.0 0.95 0.975 1.0 V
DVDD 0.95 0.975 1.0 0.95 0.975 1.0 V
DRVDD1 0.95 0.975 1.0 0.95 0.975 1.0 V
DRVDD2
1.85
1.9
1.95
1.85
1.9
1.95
V
SPIVDD 1.85 1.9 1.95 1.85 1.9 1.95 V
IAVDD1 455 605 590 693 mA
IAVDD2 585 670 810 882 mA
IAVDD3 65 72 65 73 mA
IAVDD1_SR 25 41 25 43 mA
IDVDD 340 800 405 833 mA
IDRVDD1 2 320 432 390 500 mA
IDRVDD2 25 30 25 30 mA
ISPIVDD 1 5 1 5 mA
AD9689 Data Sheet
Rev. A | Page 6 of 134
POWER CONSUMPTION
Total Power Dissipation (Including Output
Drivers)3
2.45 3.1 W
Power-Down Dissipation
265
300
mW
Standby 4 1.3 1.5 W
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 All lanes running. Power dissipation on DRVDDx changes with lane rate and number of lanes used.
3 Default mode. No DDCs used.
4 Can be controlled by the SPI.
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, sampling rate = 2.0 GHz/2.56 GHz, clock divider = 2, 1.7 V p-p full-scale differential input, input amplitude (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 2.
2.0 GSPS 2.6 GSPS
Parameter 2 Min Typ Max Min Typ Max Unit
NOISE DENSITY 3
Full Scale = 1.7 V p-p
−154.2
−152
dBFS/Hz
Full Scale = 2.0 V p-p −155.3 −154 dBFS/Hz
CODE ERROR RATE (CER)
AVDD1 = 0.975 V 7 × 10−15 9 × 10−9 Errors
AVDD1 = 1.0 V 3 × 10−15 4.5 × 10−10
Errors
SIGNAL-TO-NOISE RATIO (SNR)
fIN = 155 MHz 63.7 61.3 dBFS
fIN = 155 MHz (Full Scale = 2.0 V p-p) 65.0 62.5 dBFS
fIN = 750 MHz 63.1 61.0 dBFS
fIN = 900 MHz 60.2 62.7 60.9 dBFS
fIN = 1800 MHz 60.9 56.0 59.7 dBFS
fIN = 2100 MHz 59.9 59.3 dBFS
fIN = 3300 MHz 58.3 58.0 dBFS
fIN = 4350 MHz (Full Scale = 1.1 V p-p) 54.4 54.0 dBFS
fIN = 5530 MHz (Full Scale = 1.1 V p-p) 53.1 53.0 dBFS
SIGNAL-TO-NOISE-AND-DISTORTION RATIO (SINAD)
fIN = 155 MHz 63.5 61.2 dBFS
fIN = 155 MHz (Full Scale = 2.0 V p-p) 64.7 62.4 dBFS
fIN = 750 MHz 62.8 60.7 dBFS
fIN = 900 MHz 59.6 62.5 60.5 dBFS
fIN = 1800 MHz 60.8 52.4 59.4 dBFS
fIN = 2100 MHz 59.7 59.1 dBFS
fIN = 3300 MHz 55.3 56.6 dBFS
fIN = 4350 MHz (Full Scale = 1.1 V p-p) 53.2 51.0 dBFS
fIN = 5530 MHz (Full Scale = 1.1 V p-p) 52.3 49.5 dBFS
EFFECTIVE NUMBER OF BITS (ENOB)
fIN = 155 MHz 10.3 9.9 Bits
fIN = 155 MHz (Full Scale = 2.0 V p-p) 10.5 10.1 Bits
fIN = 750 MHz 10.1 9.8 Bits
fIN = 900 MHz 9.6 10.1 9.8 Bits
fIN = 1800 MHz 9.8 8.4 9.6 Bits
fIN = 2100 MHz 9.6 9.5 Bits
fIN = 3300 MHz 8.9 9.1 Bits
fIN = 4350 MHz (Full Scale = 1.1 V p-p) 8.6 8.2 Bits
fIN = 5530 MHz (Full Scale = 1.1 V p-p) 8.4 7.9 Bits
Data Sheet AD9689
Rev. A | Page 7 of 134
2.0 GSPS 2.6 GSPS
Parameter 2 Min Typ Max Min Typ Max Unit
SPURIOUS FREE DYNAMIC RANGE (SFDR), SECOND OR THIRD
HARMONIC4, 5
fIN = 155 MHz 77 78 dBFS
fIN = 155 MHz (Full Scale = 2.0 V p-p) 77 78 dBFS
fIN = 750 MHz 77 73 dBFS
f
IN
= 900 MHz
66
78
74
dBFS
fIN = 1800 MHz 76 58 73 dBFS
fIN = 2100 MHz 76 73 dBFS
fIN = 3300 MHz 60 64 dBFS
fIN = 4350 MHz (Full Scale = 1.1 V p-p) 61 60 dBFS
fIN = 5530 MHz (Full Scale = 1.1 V p-p) 62 59 dBFS
WORST OTHER, EXCLUDING SECOND OR THIRD HARMONIC
fIN = 155 MHz −99 −96 dBFS
fIN = 155 MHz (Full Scale = 2.0 V p-p) −95 −98 dBFS
fIN = 750 MHz −100 −97 dBFS
fIN = 900 MHz −94 −80 −96 dBFS
fIN = 1800 MHz −91 −88 −74 dBFS
fIN = 2100 MHz −86 −94 dBFS
fIN = 3300 MHz −85 −85 dBFS
f
IN
= 4350 MHz (Full Scale = 1.1 V p-p)
−83
−84
dBFS
fIN = 5530 MHz (Full Scale = 1.1 V p-p) −82 −82 dBFS
TWO-TONE INTERMODULATION DISTORTION (IMD),
AIN1 AND AIN2 = −8.0 dBFS
fIN1 = 1841 MHz, fIN2 = 1846 MHz −72 −72 dBFS
fIN1 = 2137 MHz, fIN2 = 2142 MHz −74 −76 dBFS
CROSSTALK
6
>90
>90
dB
ANALOG INPUT BANDWIDTH, FULL POWER7 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 AN-835 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 The input configuration component values are found in Table 9. Refer to Table 10 for the recommended buffer settings.
5 Figure 79 shows the differential transformer coupled configuration. Figure 80 is the input network configuration for frequencies > 5 GHz.
6 Crosstalk is measured at 950 MHz with a −2.0 dBFS analog input on one channel, and no input on the adjacent channel.
7 Full power bandwidth is the bandwidth of operation in which proper ADC performance can be achieved.
AD9689 Data Sheet
Rev. A | Page 8 of 134
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, −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 2.6 GHz 2 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
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
SYNCHRONIZATION 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 AD9689
Rev. A | Page 9 of 134
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, 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.
2.0 GSPS 2.6 GSPS
Parameter Min Typ Max Min Typ Max Unit
CLOCK
Clock Rate at CLK+/CLK− Pins 6 6 GHz
Sample Rate2 1200 2000 2100 1900 2600 2700 MSPS
Clock Pulse Width High 238.096 185.185 ps
Clock Pulse Width Low 238.096 185.185 ps
OUTPUT PARAMETERS
Unit Interval (UI)3 62.5 66.67 592.6 62.5 66.67 592.6 ps
Rise Time (tR) (20% to 80% into 100 Ω Load) 26 26 ps
Fall Time (tF) (20% to 80% into 100 Ω Load) 26 26 ps
Phase-Locked Loop (PLL) Lock Time 5 5 ms
Data Rate per Channel (Nonreturn to Zero)4 1.6875 13 16 1.6875 13 16 Gbps
LATENCY 5
Pipeline Latency6 75 75 Clock cycles
Fast Detect Latency 26 26 Clock cycles
NCO Channel Selection to Output 8 8 Clock cycles
WAKE-UP TIME
Standby 400 400 µs
Power-Down 15 15 ms
APERTURE
Delay (tA) 250 250 ps
Uncertainty (Jitter, tJ) 55 55 fs rms
Out of Range Recovery Time 1 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.
AD9689 Data Sheet
Rev. A | Page 10 of 134
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 for SPI Reads Period of the SCLK 20 ns
tCLK for SPI Writes Period of the SCLK 10 ns
tS Setup time between CSB and SCLK 2 ns
tH Hold time between CSB and SCLK 2 ns
tHIGH for SPI Reads Minimum period that SCLK must be in a logic high state 8 ns
tHIGH for SPI Writes Minimum period that SCLK must be in a logic high state 4 ns
tLOW for SPI Reads Minimum period that SCLK must be in a logic low state 8 ns
tLOW for SPI Writes Minimum period that SCLK must be in a logic low state 4 ns
t
ACCESS
Maximum time delay between the falling edge of SCLK and
output data valid for a read operation
5
8
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)
2 ns
Timing Diagrams
A B C D E F G H I J CONVERTER0
SAMPLE N – 75 MSB
SERDOUT0–
SERDOUT0+
CLK–
CLK+
CLK–
CLK+
A B C D E F G H I J CONVERTER0
SAMPLE N – 75 LSB
SERDOUT1–
SERDOUT1+
A B C D E F G H I J CONVERTER0
SAMPLE N – 74 MSB
SERDOUT2–
SERDOUT2+
A B C D E F G H I J CONVERTER0
SAMPLE N – 74 LSB
SERDOUT3–
SERDOUT3+
A B C D E F G H I J CONVERTER1
SAMPLE N – 75 MSB
SERDOUT4–
SERDOUT4+
A B C D E F G H I J CONVERTER1
SAMPLE N – 75 LSB
SERDOUT5–
SERDOUT5+
A B C D E F G H I J CONVERTER1
SAMPLE N – 74 MSB
SERDOUT6–
SERDOUT6+
A B C D E F G H 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
15550-002
Figure 2. Data Output Timing Diagram
Data Sheet AD9689
Rev. A | Page 11 of 134
CLK–
CLK+
SYSREF–
SYSREF+
t
H_SR
t
SU_SR
15550-003
Figure 3. CLK+ to SYSREF+ Setup and Hold Timing Diagram
SCLK
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
15550-004
Figure 4. SPI Interface Timing Diagram
AD9689 Data Sheet
Rev. A | Page 12 of 134
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 (T
J
)
−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 θJC_TOP ΨJB Unit
BP-196-41 16.26 1.4 5.44 °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 AD9689
Rev. A | Page 13 of 134
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
1
DENOTES CLOCK DOMAIN.
2
DENOTES SYSREF± DOMAIN.
3
DENOTES ISOLATION DOMAIN.
123 45678910 11 12 13 14
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
15550-005
Figure 5. Pin Configuration (Top View)
AD9689 Data Sheet
Rev. A | Page 14 of 134
Table 8. Pin Function Descriptions19F
1
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 AVDD120F
2 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 AGND21F
3 Ground Ground Reference for SYSREF±.
K1 to K14 AGND22F
4 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/output/
do not
connect (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 AD9689
Rev. A | Page 15 of 134
Pin No. Mnemonic Type Description
Digital Controls
L5 CSB Input SPI Chip Select (Active Low).
L6 SCLK Input SPI Serial Clock.
L7 SDIO Input/output SPI Serial Data Input/Output.
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.
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.
AD9689 Data Sheet
Rev. A | Page 16 of 134
TYPICAL PERFORMANCE CHARACTERISTICS
2.0 GSPS
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 = 2.0 GHz, clock divider = 2, 1.7 V p-p full-scale differential input, input amplitude (AIN) = −2.0 dBFS,
TJ = 70°C (TA = 25°C), 128k fast Fourier transform (FFT) sample, unless otherwise noted. See Table 10 for the recommended settings.
0
–135
–120
–90
–60
–45
–30
–15
076066557047528519095
AMPLITUDE (dB)
fIN
(MHz)
–105
–75
380 950855
A
IN
= –2dBFS
SNRFS = 63.7dB
SFDR = 77dBFS
ENOB = 10.3 BITS
NSD = –153.7dBFS/Hz
BUFFER CURRENT = 300µA
15550-406
Figure 6. Single-Tone FFT at fIN = 155 MHz
076066557047528519095
fIN
(MHz)
380 950
855
0
–135
–120
–90
–60
–45
–30
–15
AMPLITUDE (dB)
–105
–75
A
IN
= –2dBFS
SNRFS = 65.0dB
SFDR = 77dBFS
ENOB = 10.5 BITS
NSD = –155.0dBFS/Hz
BUFFER CURRENT = 300µA
15550-407
Figure 7. Single-Tone FFT at fIN = 155 MHz, Full-Scale Voltage = 2.04 V p-p
076066557047528519095
fIN
(MHz)
380 950855
0
–135
–120
–90
–60
–45
–30
–15
AMPLITUDE (dB)
–105
–75
A
IN
= –2dBFS
SNRFS = 63.1dB
SFDR = 77dBFS
ENOB = 10.1 BITS
NSD = –153.1dBFS/Hz
BUFFER CURRENT = 300µA
15550-408
Figure 8. Single-Tone FFT at fIN = 750 MHz
076066557047528519095
fIN
(MHz)
380 950855
0
–135
–120
–90
–60
–45
–30
–15
AMPLITUDE (dB)
–105
–75
A
IN
= –2dBFS
SNRFS = 62.7dB
SFDR = 78dBFS
ENOB = 10.1 BITS
NSD = –152.7dBFS/Hz
BUFFER CURRENT = 300µA
15550-409
Figure 9. Single-Tone FFT at fIN = 905 MHz
076066557047528519095
fIN
(MHz)
380 950855
0
–135
–120
–90
–60
–45
–30
–15
AMPLITUDE (dB)
–105
–75
A
IN
= –2dBFS
SNRFS = 60.9dB
SFDR = 76dBFS
ENOB = 9.8 BITS
NSD = –150.9dBFS/Hz
BUFFER CURRENT = 500µA
15550-410
Figure 10. Single-Tone FFT at fIN = 1807 MHz
076066557047528519095
fIN
(MHz)
380 950855
0
–135
–120
–90
–60
–45
–30
–15
AMPLITUDE (dB)
–105
–75
A
IN
= –2dBFS
SNRFS = 59.9dB
SFDR = 76dBFS
ENOB = 9.6 BITS
NSD = –149.9dBFS/Hz
BUFFER CURRENT = 700µA
15550-411
Figure 11. Single-Tone FFT at fIN = 2100 MHz
Data Sheet AD9689
Rev. A | Page 17 of 134
076066557047528519095
fIN
(MHz)
380 950
855
0
–135
–120
–90
–60
–45
–30
–15
AMPLITUDE (dB)
–105
–75
A
IN
= –2dBFS
SNRFS = 58.3dB
SFDR = 60dBFS
ENOB = 8.9 BITS
NSD = –148.3dBFS/Hz
BUFFER CURRENT = 700µA
15550-412
Figure 12. Single-Tone FFT at fIN = 3300 MHz
0
–135
–120
–90
–60
–45
–30
–15
AMPLITUDE (dB)
–105
–75
A
IN
= –2dBFS
SNRFS = 54.4dB
SFDR = 61dBFS
ENOB = 8.6 BITS
NSD = –144.4dBFS/Hz
BUFFER CURRENT = 900µA
15550-413
0760665
570475
28519095
fIN
(MHz)
380 950
855
Figure 13. Single-Tone FFT at fIN = 4350 MHz; Full-Scale Voltage = 1.1 V p-p
076066557047528519095
fIN
(MHz)
380 950855
0
–135
–120
–90
–60
–45
–30
–15
AMPLITUDE (dB)
–105
–75
A
IN
= –2dBFS
SNRFS = 53.1dB
SFDR = 62dBFS
ENOB = 8.4 BITS
NSD = –143.1dBFS/Hz
BUFFER CURRENT = 900µA
15550-414
Figure 14. Single-Tone FFT at fIN = 5400 MHz; Full-Scale Voltage = 1.1 V p-p
20
30
40
50
60
70
80
155
355
555
755
955
1155
1355
1555
1755
1955
2155
2355
2555
2755
2955
3155
3355
3555
3755
3955
SNR/SFDR (dBFS)
INPUT FREQUENCY (MHz)
300µA, SFDR
300µA, SNR
500µA, SFDR
500µA, SNR
700µA, SFDR
700µA, SNR
15550-415
Figure 15. SNR/SFDR vs. Input Frequency (fIN) for Various Buffer Currents
155
355
555
755
955
1155
1355
1555
1755
1955
2155
2355
2555
2755
2955
3155
3355
3555
3755
3955
INPUT FREQUENCY (MHz)
15550-416
–90
–80
–85
–75
–70
–65
–60
–55
–50
–40
–45
HD2 (dBFS)
300µA
500µA
700µA
Figure 16. HD2 vs. Input Frequency (fIN) for Various Buffer Currents
–90
–80
–70
–60
–50
–30
–40
155
355
555
755
955
1155
1355
1555
1755
1955
2155
2355
2555
2755
2955
3155
3355
3555
3755
3955
HD3 (dBFS)
INPUT FREQUENCY (MHz)
15550-417
300µA
500µA
700µA
Figure 17. HD3 vs. Input Frequency (fIN) for Various Buffer Currents
AD9689 Data Sheet
Rev. A | Page 18 of 134
0
–135
–120
–90
–60
–45
–30
–15
–105
–75
0125 250 375 500 625 750 875 1000
AMPLITUDE (dBFS)
FREQUENCY (MHz)
AIN1 AND AIN2 = –8dBFS
SFDR = 72dBFS
IMD2 = 82dBFS
IMD3 = 72dBFS
BUFFER CURRENT = 500µA
15550-418
Figure 18. Two-Tone FFT; fIN1 = 1841 MHz, fIN2 = 1846 MHz;
AIN1 and AIN2 = −8 dBFS
0
–135
–120
–90
–60
–45
–30
–15
–105
–75
0125 250 375 500 625 750 875 1000
AMPLITUDE (dBFS)
FREQUENCY (MHz)
A
IN1
AND A
IN2
= –8dBFS
SFDR = 74dBFS
IMD2 = 77dBFS
IMD3 = 74dBFS
BUFFER CURRENT = 700µA
15550-419
Figure 19. Two-Tone FFT; fIN1 = 2137 MHz, fIN2 = 2142 MHz;
AIN1 and AIN2 = −8 dBFS
0
–135
–120
–90
–60
–45
–30
–15
–105
–75
–60 –45 –30 –15 015 30 45 60
AMPLITUDE (dBFS)
FREQUENCY (MHz)
15550-420
AIN1 AND AIN2 = –8dBFS
NCO FREQUENCY = 942.5MHz
SFDR = 91dBFS
BUFFER CURRENT = 700µA
Figure 20. Two-Tone FFT; fIN1 = 947.5 MHz, fIN2 = 1855.5 MHz
fCLK = 1.96608 GHz; Decimation Ratio = 16, NCO Frequency = 942.5 MHz
0
–135
–120
–90
–60
–45
–30
–15
–105
–75
–60 –45 –30 –15 015 30 45 60
AMPLITUDE (dBFS)
FREQUENCY (MHz)
AIN1 AND AIN2 = –8dBFS
NCO FREQUENCY = 1.842GHz
SFDR = 99dBFS
BUFFER CURRENT = 700µA
15550-421
Figure 21. Two-Tone FFT; fIN1 = 947.5 MHz, fIN2 = 1855.5 MHz
fCLK = 1.96608 GHz; Decimation Ratio = 16, NCO Frequency = 1842.5 MHz
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
–20
–10
0
–90
–84
–78
–72
–66
–60
–54
–48
–42
–36
–30
–24
–18
–12
SFDR/IMD3 (dBc AND dBFS)
INPUT AMPLITUDE (dBFS)
SFDR (dBc)
SFDR (dBFS)
IMD3 (dBc)
IMD3 (dBFS)
15550-422
Figure 22. Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with
fIN1 = 1841.5 MHz, fIN2 = 1846.5 MHz
–120
–140
–100
–80
–60
–40
–20
0
–90
–84
–78
–72
–66
–60
–54
–48
–42
–36
–30
–24
–18
–12
SFDR/IMD3 (dBc AND dBFS)
INPUT AMPLITUDE (dBFS)
SFDR (dBc)
SFDR (dBFS)
IMD3 (dBc)
IMD3 (dBFS)
15550-423
Figure 23. Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with
fIN1 = 2137.5 MHz, fIN2 = 2142.5 MHz
Data Sheet AD9689
Rev. A | Page 19 of 134
–40
–20
0
20
40
60
80
100
120
–85
–81
–77
–73
–69
–65
–61
–57
–53
–49
–45
–41
–37
–33
–29
–25
–21
–17
–13
–9
–5
SNR/SFDR (dBc AND dBFS)
INPUT AMPLITUDE (dBFS)
SNR (dBFS)
SFDR (dBFS)
SFDR (dBc)
SNR (dBc)
15550-424
Figure 24. SNR/SFDR vs. Input Amplitude (AIN), fIN = 900 MHz
–40
–20
0
20
40
60
80
100
120
–85
–81
–77
–73
–69
–65
–61
–57
–53
–49
–45
–41
–37
–33
–29
–25
–21
–17
–13
–9
–5
SNR/SFDR (dBc AND dBFS)
INPUT AMPLITUDE (dBFS)
SNR (dBFS)
SFDR (dBFS)
SFDR (dBc)
SNR (dBc)
15550-425
Figure 25. SNR/SFDR vs. Input Amplitude (AIN), fIN = 1800 MHz
0
10
20
30
40
50
60
70
80
90
–10 010 20 30 40 50 60 70 80 90 100 110 120
SNR/SFDR (dBFS)
JUNCTION TEMPERATURE (°C)
SNR
SFDR
15550-426
Figure 26. SNR/SFDR vs. Junction Temperature (TJ), fIN = 900 MHz
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
POWER (W)
AVDD1 + AVDD2 + AVDD3 POWER
DRVDD1 + DRVDD2 POWER
DVDD + SPIVDD POWER
AVERAGE OF TOTAL POWER (W)
–10 010 20 30 40 50 60 70 80 90 100 110 120
JUNCTION TEMPERATURE (°C)
15550-427
Figure 27. Power vs. Junction Temperature (TJ), fIN = 900 MHz
47
49
51
53
55
57
59
61
63
65
155.3
467.8
780.3
1092.8
1405.3
1717.8
2020.3
2332.8
2645.3
2957.8
3270.3
3582.8
3895.3
SNR (dBFS)
ANALOG INPUT FREQUENCY (MHz)
0.2V
0.3V
0.5V
0.8V
1.2V
1.8V
2.0V
15550-428
Figure 28. SNR vs. Analog Input Frequency (fIN) for Various Clock Amplitude
in Differential Peak-to-Peak Voltages
0
10
20
30
40
50
60
70
80
90
1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1
SNR/SFDR (dBFS)
SAMPLE FREQUENCY (GHz)
SNR
SFDR
15550-429
Figure 29. SNR/SFDR vs. Sample Frequency (fS), fIN = 900 MHz
AD9689 Data Sheet
Rev. A | Page 20 of 134
0
10
20
30
40
50
60
70
80
1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1
SNR/SFDR (dBFS)
SAMPLE FREQUENCY (GHz)
SNR
SFDR
15550-430
Figure 30. SNR/SFDR vs. Sample Frequency (fS), fIN = 1.8 GHz
0
0.5
1.0
1.5
2.0
2.5
3.0
1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1
POWER DISSIPATION (W)
SAMPLE FREQUENCY (GHz)
15550-431
AVDD1 + AVDD2 + AVDD3 POWER
DRVDD1 + DRVDD2 POWER
DVDD + SPIVDD POWER
AVERAGE OF TOTAL POWER
Figure 31. Power Dissipation vs. Sample Frequency (fS), fIN = 1.8 GHz
–15
–14
–13
–12
–11
–10
–9
–8
–7
–6
–5
–4
–3
100 2100 4100 6100 8100 10100 12100
AMPLITUDE (dB)
FREQUENCY (MHz)
15550-232
Figure 32. Input Bandwidth (See Figure 80 for the Input Configuration)
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
3.8 LSB 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
NUMBER OF HITS
OUTPUT CODE
15550-433
Figure 33. Input Referred Noise Histogram
–6
–4
–2
0
2
4
6
02000 4000 6000 8000 10000 12000 14000 16000
INL (LSB)
OUTPUT CODE
15550-434
Figure 34. INL, fIN = 155 MHz
–0.8
–0.6
–0.4
–0.2
0
0.2
0.4
0.8
0.6
02000 4000 6000 8000 10000 12000 14000 16000
DNL (LSB)
OUTPUT CODE
15550-435
Figure 35. DNL, fIN = 155 MHz
Data Sheet AD9689
Rev. A | Page 21 of 134
2.6 GSPS
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 = 2.56 GHz, clock divider = 2, 1.7 V p-p full-scale differential input, input amplitude (AIN) = −2.0 dBFS,
TJ = 70°C (TA = 25°C), 128 k FFT sample, unless otherwise noted. See Table 10 for the recommended settings.
15550-106
0
–120
–90
–60
–45
–30
–15
AMPLITUDE (dB)
–105
–75
AIN = –2dBFS
SNRFS = 61.3dB
SFDR = 78dBc
ENOB = 10.2 BITS
NSD = –152.4dBFS/Hz
BUFFER CURRENT = 300µA
1.05G0900M750M600M450M300M150M 1.20G
Figure 36. Single-Tone FFT at fIN = 155 MHz
–120
–80
–60
–40
–20
0
AMPLITUDE (dB)
f
IN
(Hz)
A
IN
= –2dBFS
SNR = 62.5dBFS
SFDR = 78dBFS
ENOB = 10.4 BITS
NSD = –153.6dBFS/Hz
BUFFER CURRENT = 300µA
15550-107
01.05G900M750M600M450M300M
150M 1.20G
Figure 37. Single-Tone FFT at fIN = 155 MHz, Full-Scale Voltage = 2.04 V p-p
0
–120
–90
–60
–45
–30
–15
AMPLITUDE (dB)
–105
–75
A
IN
= –2dBFS
SNRFS = 61.0dB
SFDR = 73dBFS
ENOB = 10.1 BITS
NSD = –152.1dBFS/Hz
BUFFER CURRENT = 300µA
0900M750M600M450M300M150M
f
IN
(Hz)
1.20G
15550-108
Figure 38. Single-Tone FFT at fIN = 750 MHz
0
–120
–90
–60
–45
–30
–15
1.05G
0900M
750M
600M450M
300M
150M
AMPLITUDE (dB)
fIN
(Hz)
–105
–75
1.20G
15550-109
A
IN
= –2dBFS
SNRFS = 60.9dB
SFDR = 74dBFS
ENOB = 10.1 BITS
NSD = –152.0dBFS/Hz
BUFFER CURRENT = 300µA
Figure 39. Single-Tone FFT at fIN = 905 MHz
0
–120
–90
–60
–45
–30
–15
1.05G0900M
750M600M
450M
300M150M
AMPLITUDE (dB)
f
IN (Hz)
–105
–75
1.20G
15550-110
AIN = –2dBFS
SNRFS = 59.7dB
SFDR = 73dBFS
ENOB = 9.6 BITS
NSD = –150.8dBFS/Hz
BUFFER CURRENT = 500µA
Figure 40. Single-Tone FFT at fIN = 1807 MHz
0
–135
–120
–90
–60
–45
–30
–15
01.05G900M750M600M450M300M150M
AMPLITUDE (dB)
fIN
(Hz)
–105
–75
1.20G
A
IN
= –2dBFS
SNRFS = 59.3dB
SFDR = 73dBFS
ENOB = 9.5 BITS
NSD = –150.4dBFS/Hz
BUFFER CURRENT = 500µA
15550-111
Figure 41. Single-Tone FFT at fIN = 2100 MHz
AD9689 Data Sheet
Rev. A | Page 22 of 134
0
–120
–90
–60
–45
–30
–15
1.05G0900M750M600M450M300M150M
AMPLITUDE (dB)
fIN
(Hz)
–105
–75
1.20G
15550-112
A
IN
= –2dBFS
SNRFS = 58.0dB
SFDR = 64dBFS
ENOB = 9.1 BITS
NSD = –149.0dBFS/Hz
BUFFER CURRENT = 700µA
Figure 42. Single-Tone FFT at fIN = 3300 MHz
0
–120
–90
–60
–45
–30
–15
1.05G0900M750M600M
450M300M150M
AMPLITUDE (dB)
f
IN
(Hz)
–105
–75
1.20G
15550-113
A
IN
= –2dBFS
SNRFS = 54.0dB
SFDR = 60dBFS
ENOB = 8.2 BITS
NSD = –145.1dBFS/Hz
BUFFER CURRENT = 700µA
Figure 43. Single-Tone FFT at fIN = 4350 MHz; Full-Scale Voltage = 1.1 V p-p
01.05G900M750M600M450M300M150M
fIN (Hz)
0
–120
–90
–60
–45
–30
–15
AMPLITUDE (dB)
–105
–75
1.20G
15550-114
AIN = –2dBFS
SNRFS = 53.0dB
SFDR = 59dBFS
ENOB = 7.9 BITS
NSD = –144.1dBFS/Hz
BUFFER CURRENT = 700µA
Figure 44. Single-Tone FFT at fIN = 5400 MHz; Full-Scale Voltage = 1.1 V p-p
30
35
40
45
50
55
60
65
70
75
80
155
355
555
755
955
1155
1355
1555
1755
1955
2155
2355
2555
2755
2955
3155
3355
3555
3755
3955
SNR/SFDR (dBFS)
INPUT FREQUENCY (MHz)
300µA, SFDR
300µA, SNR
500µA, SFDR
500µA, SNR
700µA, SFDR
700µA, SNR
15550-115
Figure 45. SNR/SFDR vs. Input Frequency (fIN) for Various Buffer Currents
155
355
555
755
955
1155
1355
1555
1755
1955
2155
2355
2555
2755
2955
3155
3355
3555
3755
3955
INPUT FREQUENCY (MHz)
15550-116
–80
–75
–70
–65
–60
–55
–50
–45
HD2 (dBFS)
300µA
500µA
700µA
Figure 46. Second Harmonics (HD2) vs. Input Frequency (fIN) for Various
Buffer Currents
–90
–85
–80
–75
–70
–65
–60
–55
–50
–45
–40
155
355
555
755
955
1155
1355
1555
1755
1955
2155
2355
2555
2755
2955
3155
3355
3555
3755
3955
HD3 (dBFS)
INPUT FREQUENCY (MHz)
15550-117
300µA
500µA
700µA
Figure 47. Third Harmonics (HD3) vs. Input Frequency (fIN) for Various Buffer
Currents
Data Sheet AD9689
Rev. A | Page 23 of 134
–120
–100
–80
–60
–40
–20
0
0160 320 480 640 800 960 1120 1280
AMPLITUDE (dBFS)
FREQUENCY (MHz)
15550-118
A
IN1
AND A
IN2
= –8dBFS
SFDR = 72dBFS
IMD2 = 72dBFS
IMD3 = 78dBFS
BUFFER CURRENT = 500µA
Figure 48. Two-Tone FFT; fIN1 = 1841 MHz, fIN2 = 1846 MHz;
AIN1 and AIN2 = −8 dBFS
–120
–100
–80
–60
–40
–20
0
0160 320 480 640 800 960 1120 1280
AMPLITUDE (dBFS)
FREQUENCY (MHz)
15550-119
AIN1 AND AIN2 = –8dBFS
SFDR = 76dBFS
IMD2 = 78dBFS
IMD3 = 76dBFS
BUFFER CURRENT = 700µA
Figure 49. Two-Tone FFT; fIN1 = 2137 MHz, fIN2 = 2142 MHz;
AIN1 and AIN2 = −8 dBFS
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
–20
–10
0
–122.88 –92.16 –61.44 –30.72 030.72 61.44 92.16 122.88
AMPLITUDE (dB)
FREQUENCY (MHz)
15550-120
AIN1 AND AIN2 = –8dBFS
NCO FREQUENCY = 1.84GHz
SFDR = 77dBFS
BUFFER CURRENT = 700µA
Figure 50. Two-Tone FFT; fIN1 = 1846.5 MHz, fIN2 = 2142.5 MHz
fCLK = 2.4576 GHz; Decimation Ratio = 10, NCO Frequency = 1840 MHz
–130
–120
–110
–100
–90
–80
–70
–60
–50
–40
–30
–20
–10
0
–122.88 –92.16 –61.44 –30.72 030.72 61.44 92.16 122.88
AMPLITUDE (dB)
FREQUENCY (MHz)
15550-121
A
IN1
AND A
IN2
= –8dBFS
NCO FREQUENCY = 2.14GHz
SFDR = 84dBFS
BUFFER CURRENT = 700µA
Figure 51. Two-Tone FFT; fIN1 = 1846.5 MHz, fIN2 = 2142.5 MHz
fCLK = 2.4576 GHz; Decimation Ratio = 10, NCO Frequency = 2140 MHz
–130
–120
–110
–100
–90
–80
–70
–60
SFDR/IMD3 (dBc AND dBFS)
–50
–40
–30
–20
–10
0
–90 –84 –78 –72 –66 –60 –54 –48
INPUT AMPLITUDE (dBFS)
–42 –36 –30 –24 –18 –12
IMD3 (dBc)
IMD3 (dBFS)
SFDR (dBc)
SFDR (dBFS)
15550-122
Figure 52. Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with
fIN1 = 1841.5 MHz, fIN2 = 1846.5 MHz
–130
–120
–110
–100
–90
–80
–70
–60
SFDR/IMD3 (dBc AND dBFS)
–50
–40
–30
–20
–10
0
–90 –84 –78 –72 –66 –60 –54 –48
INPUT AMPLITUDE (dBFS)
–42 –36 –30 –24 –18 –12
IMD3 (dBc)
IMD3 (dBFS)
SFDR (dBc)
SFDR (dBFS)
15550-123
Figure 53. Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with
fIN1 = 2137.5 MHz, fIN2 = 2142.5 MHz
AD9689 Data Sheet
Rev. A | Page 24 of 134
–40
–30
–20
–10
0
10
20
30
40
50
60
70
80
90
100
110
–90 –82 –74 –66 –58 –50 –42 –34 –26 –18 –10 –2
SNR/SFDR (dBc AND dBFS)
INPUT AMPLITUDE (dBFS)
SNR (dBc)
SNR (dBFS)
SFDR (dBc)
SFDR (dBFS)
15550-124
Figure 54. SNR/SFDR vs. Input Amplitude (AIN), fIN = 900 MHz
–40
–30
–20
–10
0
10
20
30
40
50
60
70
80
90
100
110
–90 –82 –74 –66 –58 –50 –42 –34 –26 –18 –10 –2
SNR/SFDR (dBc AND dBFS)
INPUT AMPLITUDE (dBFS)
SNR (dBc)
SNR (dBFS)
SFDR (dBc)
SFDR (dBFS)
15550-125
Figure 55. SNR/SFDR vs. Input Amplitude (AIN), fIN = 1800 MHz
50
55
60
65
70
75
–10 010 20 30 40 50 60 70 80 90 100 110 120
SNR/SFDR (dBFS)
JUNCTION TEMPERATURE (°C)
SNR
SFDR
15550-126
Figure 56. SNR/SFDR vs. Junction Temperature (TJ), fIN = 900 MHz
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
–10 010 20 30 40 50 60 70 80 90 100 110 120
POWER (W)
JUNCTION TEMPERATURE (°C)
AVDD1 POWER/AVDD2 POWER/AVDD3 POWER (W)
DRVDD1 POWER/DRVDD2 POWER (W)
DVDD POWER/SPIVDD POWER (W)
TOTAL POWER (W)
15550-127
Figure 57. Power vs. Junction Temperature (TJ), fIN = 900 MHz
47
49
51
53
55
57
59
61
63
155.3 655.3 1155.3 1655.3 2155.3 2655.3 3155.3 3655.3
SNR (dBFS)
ANALOG INPUT FREQUENCY (MHz)
0.2V
0.3V
0.5V
0.8V
1.2V
1.8V
2.0V
15550-128
Figure 58. SNR vs. Analog Input Frequency (fIN) for Various Clock Amplitude
in Differential Peak-to-Peak Voltages
0
10
20
30
40
50
60
70
80
90
1800 1900 2000 2100 2200 2300 2400 2500 2600 2700
SNR/SFDR (dBFS)
SAMPLE FREQUENCY (MHz)
SNR
SFDR
15550-129
Figure 59. SNR/SFDR vs. Sample Frequency (fS), fIN = 900 MHz
Data Sheet AD9689
Rev. A | Page 25 of 134
0
10
20
30
40
50
60
70
80
1800 1900 2000 2100 2200 2300 2400 2500 2600 2700
SNR/SFDR (dBFS)
SAMPLE FREQUENCY (MHz)
15550-130
SNR
SFDR
Figure 60. SNR/SFDR vs. Sample Frequency (fS), fIN = 1.8 GHz
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
1800 1900 2000 2100 2200 2300 2400 2500 2600 2700
POWER DISSIPATION (W)
SAMPLE FREQUENCY (MHz)
AVDD1 POWER/AVDD2 POWER/AVDD3 POWER
DRVDD1 POWER/DRVDD2 POWER
DVDD POWER/SPIVDD POWER
TOTAL POWER
15550-131
Figure 61. Power Dissipation vs. Sample Frequency (fS), fIN = 1.8 GHz
–15
–14
–13
–12
–11
–10
–9
–8
–7
–6
–5
–4
–3
100 2100 4100 6100 8100 10100 12100
AMPLITUDE (dB)
FREQUENCY (MHz)
15550-232
Figure 62. Input Bandwidth (See Figure 80 for the Input Configuration)
0
50000
100000
150000
200000
250000
300000
350000
400000
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
NUMBER OF HITS
OUTPUT CODE
4.6 LSB RMS
15550-133
Figure 63. Input Referred Noise Histogram
–4
–3
–2
–1
0
1
2
3
4
5
6
02000 4000 6000 8000 10000 12000 14000 16000
INL (LSB)
OUTPUT CODE
15550-135
Figure 64. INL, fIN = 155 MHz
–0.6
–0.4
–0.2
0
0.2
0.4
0.6
0.8
02000 4000 6000 8000 10000 12000 14000 16000
DNL (LSB)
OUTPUT CODE
15550-134
Figure 65. DNL, fIN = 155 MHz
AD9689 Data Sheet
Rev. A | Page 26 of 134
EQUIVALENT CIRCUITS
0.3pF
AVDD3
VIN+x
AVDD3
100Ω
100Ω
AVDD3
AVDD3
VIN–x
0.3pF
AVDD3
A
IN
CONTROL
(SPI)
V
CM
BUFFER
15550-037
Figure 66. Analog Inputs
106Ω
16kΩ
AVDD1
CLK+
CLK–
AVDD1
16kΩ
V
CM
= 0.65V
15550-038
Figure 67. Clock Inputs
130kΩ
2.6kΩ
10kΩ100Ω
10kΩ100Ω
1.9pF
130kΩ
DRVDD1
DRVDD1
SYNCINB+
SYNCINB–
DRGND
DRGND
DRGND
DRGND
DRGND
LEVEL
TRANSLATOR V
CM
= 0.65V
SYNCINB± PIN
CONTROL (SPI)
CMOS PATH
DRVDD1
1.9pF
15550-041
Figure 68. SYNCINB± Inputs
130kΩ
10kΩ100Ω
10kΩ
100Ω
1.9pF
130kΩ
AVDD1_SR
SYSREF+
SYSREF–
LEVEL
TRANSLATOR V
CM
= 0.65V
AVDD1_SR
1.9pF
15550-039
Figure 69. SYSREF± Inputs
OUTPUT
DRIVER
EMPHASIS/SWING
CONTROL (SPI)
DRVDD1
SERDOUTx+
x = 0, 1, 2, 3, 4, 5, 6, 7
SERDOUTx–
x = 0, 1, 2, 3, 4, 5, 6, 7
DATA+
DATA–
DRVDD1
DRGND
DRGND
15550-040
Figure 70. Digital Outputs
56kΩ
SCLK
SPIVDD
SPIVDD
ESD
PROTECTED
ESD
PROTECTED
DGND
DGND
DGND
15550-042
Figure 71. SCLK Input
Data Sheet AD9689
Rev. A | Page 27 of 134
56kΩ
CSB
SPIVDD
ESD
PROTECTED
ESD
PROTECTED
DGND
DGND
15550-043
Figure 72. CSB Input
56kΩ
SDIO
SPIVDD
SPIVDD
ESD
PROTECTED
ESD
PROTECTED
DGND
SPIVDD
DGND
SDI
SDO
DGND
DGND
15550-044
Figure 73. SDIO Input
56kΩ
PDWN/STBY
SPIVDD
ESD
PROTECTED
ESD
PROTECTED
DGND
DGND
DGND
PDWN
CONTROL (SPI)
15550-046
Figure 74. PDWN/STBY Input
VREF
AGND
AVDD2
VCM OUTPUT
TEMPERATURE DIODE
VOLTAGE OUTPUT
EXTERNAL REFERENCE
VOLTAGE INPUT
VREF PIN
CONTROL (SPI)
15550-047
Figure 75. VREF Input/Output
56kΩ
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
15550-045
Figure 76. FD_A/GPIO_A0, FD_B/GPIO_B0
SPIVDD
56kΩ
SPIVDD
ESD
PROTECTED
ESD
PROTECTED
DGND DGND
DGND
SDI
GPIO_A1/GPIO_B1
GPIO_A1/GPIO_B1
PIN CONTROL (SPI)
NCO BAND SELECT
CHIP TRANSFER
15550-247
Figure 77. GPIO_A1/GPIO_B1
AD9689 Data Sheet
Rev. A | Page 28 of 134
THEORY OF OPERATION
The AD9689 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 AD9689 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 AD9689 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 AD9689 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 AD9689 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 Ω. The equivalent circuit diagram of the
analog input termination is shown in Figure 66. 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 AD9689 is a differential buffer. The internal
common-mode voltage of the buffer is 1.4 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 78 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 Ω.
0
0
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 = Z
0
× (1.838 – j0.171)
m2
FREQUENCY = 1GHz
SDD11 = 0.352/–73.534
IMPEDANCE = Z
0
× (0.947 – j0.731)
m3
FREQUENCY = 3GHz
SDD11 = 0.496/175.045
IMPEDANCE = Z
0
× (0.337 – j0.038)
m4
FREQUENCY = 4GHz
SDD11 = 0.500/136.667
IMPEDANCE = Z
0
× (0.379 + j0.347)
m5
FREQUENCY = 5GHz
SDD11 = 0.475/79.360
IMPEDANCE = Z
0
× (0.737 + j0.889)
15550-248
Figure 78. 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 AD9689,
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 AD9689
Rev. A | Page 29 of 134
Differential Input Configurations
There are several ways to drive the AD9689, 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 79 and Table 9) because the noise
performance of most amplifiers is not adequate to achieve the
true performance of the AD9689.
For low to midrange frequencies, a double balun or double
transformer network (see Figure 79 and Table 9) is recommended
for optimum performance of the AD9689.
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 80 and
Table 9).
ADC
200Ω
C3
C2
C1
C4
R1
NOTES:
1. SEE TABLE 9 FOR COMPONENT VALUES
R2
R2
R3
C3
C2
R1 R3
MARKI
BAL-0006
15550-249
Figure 79. Differential Transformer Coupled Configuration for the AD9689
ADC
MARKI
BAL-0009
25Ω
25Ω
25Ω
0.1µF
0.1µF
0.1µF 200Ω
10Ω
25Ω 10Ω
15550-250
Figure 80. 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 μF 0.1 μF 0.4 pF 0.4 pF or open
>5000 MHz BAL-0009 25 Ω 25 Ω 10 Ω 0.1 μF 0.1 μF Open Open
AD9689 Data Sheet
Rev. A | Page 30 of 134
Input Common Mode
The analog inputs of the AD9689 are internally biased to the
common-mode voltage, as shown in Figure 82. 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:
1. Set Register 0x1908, Bit 2 to disconnect the internal
common-mode buffer from the analog input. Note that
this is a local register.
2. Set Register 0x18A6 to 0x00 to turn off the voltage reference.
3. Set Register 0x18E6 to 0x00 to turn off the temperature
diode export.
4. Set Register 0x18E3, Bit 6 to 1 to turn on the VCM export.
5. 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 81 shows the block diagram 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
15550-251
Figure 81. DC-Coupled Application Using the AD9689
Analog Input Buffer Controls and SFDR Optimization
VIN+x
100Ω
100Ω
AVDD3 AVDD3
0.3pF
AVDD3
VIN–x
AVDD3
REG
(0x0008,
0x1908)
REG (0x0008, 0x1A4C,
0x1A4D, 0x1910)
AVDD3
0.3pF
15550-252
Figure 82. Analog Input Controls
The AD9689 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 82.
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 83.
For a complete list of buffer current settings, see Table 46 and
Table 53.
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)
15550-253
Figure 83. 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
Product Frequency
Register
0x1A4C
and
Register
0x1A4D
High
Frequency
Setting
Register
0x1A48
AD9689-2600 DC to 1.3 GHz Default
(300 µA)
Default (0x14)
1.3 GHz to 2.6 GHz 500 µA Default (0x14)
>2.6 GHz 700 µA 0x54
AD9689-2000 DC to 1000 MHz
Default
(300 µA)
N/A1
1 GHz to 2 GHz 500 µA N/A
>2 GHz 700 µA N/A
1 N/A means not applicable.
Data Sheet AD9689
Rev. A | Page 31 of 134
Dither
The AD9689 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 AD9689. 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
AD9689 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.
VOLTAGE REFERENCE
A stable and accurate 0.5 V voltage reference is built into the
AD9689. 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 and
Table 53. Figure 85 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 AD9689, 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 84 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)
15550-256
Figure 84. Typical Reference Voltage (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 86 shows how the ADR130 can be used to provide the
external 0.5 V reference to the AD9689. The dashed lines show
unused blocks within the AD9689 while using the ADR130 to
provide the external reference.
ADC
CORE
INPUT FULL-SCALE
RANGE ADJUST
SPI REGISTER
(0x1910)
VREF PIN
CONTROL SPI
REGISTER
(0x18A6)
VIN+A/VIN+B
VIN–A/VIN–B
VREF
INTERNAL
0.5V
REFERENCE
GENERATOR
15550-254
INPUT
FULL-SCALE
ADJUST
Figure 85. Internal Reference Configuration and Controls
AD9689 Data Sheet
Rev. A | Page 32 of 134
VREF PIN
AND VFS
CONTROL
INPUT
FULL-SCALE
ADJUST
VREFINPUT
0.1µF 0.1µF
V
OUT
V
IN
ADC
INTERNAL
0.5V
REFERENCE
GENERATOR
SETGND
NCNC
ADR130
15550-255
Figure 86. External Reference Using the ADR130
DC OFFSET CALIBRATION
The AD9689 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 this value.
CLOCK INPUT CONSIDERATIONS
For optimum performance, drive the AD9689 sample clock
inputs (CLK+ and CLK−) with a differential signal. This 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 87 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 Ω.
0
0
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
m1
FREQUENCY = 2.001GHz
SDD11 = 0.274/–156.496
IMPEDANCE = Z
0
× (0.586 – j0.139)
m2
FREQUENCY = 2.602GHz
SDD11 = 0.319/–176.549
IMPEDANCE = Z
0
× (0.516 – j0.022)
m3
FREQUENCY = 2.996GHz
SDD11 = 0.337/169.383
IMPEDANCE = Z
0
× (0.499 – j0.070)
m4
FREQUENCY = 4.001GHz
SDD11 = 0.360/139.617
IMPEDANCE = Z
0
× (0.518 + j0.278)
m5
FREQUENCY = 5.202GHz
SDD11 = 0.364/139.617
IMPEDANCE = Z
0
× (0.761 + j0.639)
15550-257
m5
m4
m1
m2
m3
Figure 87. Differential Input Return Loss for the CLK± Inputs
Data Sheet AD9689
Rev. A | Page 33 of 134
Figure 88 shows a preferred method for clocking the AD9689.
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–
15550-258
Figure 88. Transformer-Coupled Differential Clock
Another option is to ac couple a differential LVPECL or CML
signal to the sample clock input pins, as shown in Figure 89 and
Figure 90, respectively.
ADC
CLOCK
INPUT
CLK+
CLK–
150Ω 150Ω
LVDS
DRIVER
100Ω
DIFFERENTIAL
TRACE
15550-259
Figure 89. Differential LVPECL Sample Clock
ADC
CLOCK
INPUT
CLK+
CLK–
CML
DRIVER
DIFFERENTIAL
TRACE
15550-260
Figure 90. Differential CML Sample Clock
In some instances, the RF DAC series such as the AD9172 has a
synthesizer that can output a clock output to clock the AD9689.
Figure 91 shows the arrangement where the AD9172 clock
outputs clock the AD9689.
ADC
ADC
CLOCK
INPUT
CLK+
CLK–
DAC
CLOCK
INPUT
CLKOUT+
CLKOUT–
15550-261
AD9172
Figure 91. DAC Clock Output Clocking the AD9689
AD9689 Data Sheet
Rev. A | Page 34 of 134
Clock Duty Cycle Considerations
Typical high speed ADCs use both clock edges to generate a
variety of internal timing signals. The AD9689 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 92 shows the different controls to the
AD9689 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 AD9689 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 92).
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
15550-262
Figure 92. Clock Divider Circuit
The AD9689 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 AD9689 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 AD9689 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 93 shows the
controls available to the clock dividers within AD9689. 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
15550-263
Figure 93. 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 AD9689 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 for Pin A4 and Pin
A11, as well as Pin B4 and Pin B11, as shown in Figure 94.
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
15550-264
Figure 94. Q Factor Reduction Network Recommendation for the Clock
Domain Supply
Data Sheet AD9689
Rev. A | Page 35 of 134
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.
Intermediate frequency (IF) undersampling applications are
particularly sensitive to jitter (see Figure 95).
130
120
110
100
90
80
70
60
50
40
30
10 100100010000
IDEAL 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
15550-265
Figure 95. Ideal SNR vs. Analog Input Frequency and Jitter
Treat the clock input as an analog signal when aperture jitter
may affect the dynamic range of the AD9689. 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 information about jitter
performance as it relates to ADCs.
Figure 96 shows the estimated SNR of the AD9689 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
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
10M 100M 1G 10G
SNR (dBFS)
INPUT FREQUENCY (Hz)
25
f
S
50
f
S
75
f
S
100
f
S
125
f
S
150
f
S
175
f
S
200
f
S
15550-166
Figure 96. Estimated SNR Degradation vs. Input Frequency and RMS Jitter
for the 2.6 GSPS
POWER-DOWN AND STANDBY MODE
The AD9689 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 AD9689 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. Figure 97 shows the locations of the diodes in the
AD9689 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.
ADC
AADC
B
ADC
DIGITAL
VREF
JESD204B DRIVER
TEMPERATURE DIODE
LOCATIONS
CHANNEL A, CENTRAL,
CHANNEL B
15550-267
Figure 97. Temperature Diode Locations in the Die
AD9689 Data Sheet
Rev. A | Page 36 of 134
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 may result in undefined
behavior. To ensure a proper readout, switch off all other voltage
exporting circuits as described in this section. Figure 98 shows
the block diagram of the controls that are required to enable the
diode voltage readout.
TE M P ERATURE DI ODE
LO CATION SELECT
SPI REGISTER (0x18E6)
VREF PIN
CONTROL
SPI REGISTER
(0x18A6)
CHANNEL A
CENTRAL
V
REF CHANNEL B
15550-268
Figure 98. 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 and Table 53 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 99.
Although this voltage represents the die temperature, it is
recommended to take measurements from a pair of diodes
for improved accuracy. Step 5 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.
0.80
0.75
0.70
0.65
0.60
0.55
0.50
–40 –20 0 20
JUNCTIO N T E M PE RATURE (° C)
TE M P ERAT URE D IO D E V OL TAGE ( V )
40 60 80 100
15550-269
Figure 99. 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 100.
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)
15550-270
Figure 100. Junction Temperature vs. ΔV (mV)
Data Sheet AD9689
Rev. A | Page 37 of 134
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 AD9689 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 AD9689 also records any overrange condition in any of the
eight virtual converters. For more information on the virtual
converters, refer to Figure 109. 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 101.
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, Table 47, and Table 49)
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
15550-048
Figure 101. Threshold Settings for the FD_A and FD_B Signals
AD9689 Data Sheet
Rev. A | Page 38 of 134
ADC APPLICATION MODES AND JESD204B Tx CONVERTER MAPPING
The AD9689 contains a configurable signal path that allows
different features to be enabled for different applications.
These features are controlled using the chip 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 AD9689 contains the following modes:
• Full bandwidth mode: two 14-bit ADC cores running at
full sample rate.
• DDC mode: up to four 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 AD9689
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 102 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 AD9689 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 103 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 Application
Mode
(Reg. 0x0200,
Bits[3:0])
Chip Q Ignore
(Reg. 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
Data Sheet AD9689
Rev. A | Page 39 of 134
DDC 0
I
Q
I
Q
REAL/I
CONVERTER0
Q
CONVERTER 1
REAL/I
REAL/Q
DDC 1
I
Q
I
Q
REAL/I
CONVERTER 2
Q
CONVERTER 3
REAL/I
REAL/Q
DDC 2
I
Q
I
Q
REAL/I
CONVERTER 4
Q
CONVERTER 5
REAL/I
REAL/Q
DDC 3
I
Q
I
Q
REAL/I
CONVERTER 6
Q
CONVERTER7
REAL/I
REAL/Q
OUTPUT
INTERFACE
I/Q
CROSSBAR
MUX
ADC A
SAMPLING
AT
fS
REAL/I
ADC B
SAMPLING
AT
fS
REAL/Q
15550-066
Figure 102. DDCs and Virtual Converter Mapping
REAL
I
Q
I
CONVERTER 0
Q
CONVERTER 1
ADC
ADC
90°
PHASE
Σ
JESD204B
Tx LLANES
I/Q ANALOG MIXING
M = 2
ADC
REAL REAL
I
CONVERTER 0
Q
CONVERTER 1
JESD204B
Tx L LANES
DIGITAL DOWNCONVERSION
M = 2
DIGITAL
DOWN
CONVERSION
15550-065
Figure 103. I/Q Transport Layer Mapping
AD9689 Data Sheet
Rev. A | Page 40 of 134
PROGRAMMABLE FIR FILTERS
SUPPORTED MODES
The AD9689 supports the following modes of operation (the
asterisk symbol (*) denotes convolution):
• Real 48-tap filter for each I/Q channel (see Figure 104)
• 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 105)
• DOUT_I[n] = DIN_I[n] * XY_I_XY_Q[n]
• DOUT_Q[n] = DIN_Q[n]
• Real set of two cascaded 24-tap filters for each I/Q channel
(see Figure 106)
• 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 107)
• 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 108)
• 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
xyQ [n]
DINQ [n] DOUTQ [n]
ADC A
CORE
I (REAL) 48-TAP FIR
FILTER
xyI [n]
DINI [n] DOUTI [n] I′ (REAL)
PROGRAMMABLE FILTER (PFILT)
Q′ (IMAG)
SIGNAL
PROCESSING
BLOCKS
JESD204B
INTERFACE
15550-274
Figure 104. 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
15550-275
Figure 105. Real 96-Tap Filter Configuration
Data Sheet AD9689
Rev. A | Page 41 of 134
ADC B
CORE
Q (IMAG) DIN
Q
[n]
DOUT
Q
[n]
ADC A
CORE
I (REAL) 24-TAP FIR
FILTER
x
I
[n]
24-TAP FIR
FILTER
y
I
[n]
24-TAP FIR
FILTER
y
Q
[n]
24-TAP FIR
FILTER
x
Q
[n]
DIN
I
[n] DOUT
I
[n] I′ (REAL)
PROGRAMMABLE FILTER (PFILT)
Q′ (IMAG)
SIGNAL
PROCESSING
BLOCKS
JESD204B
INTERFACE
15550-276
Figure 106. Real, Two Cascaded, 24-Tap Filter Configuration
ADC B
CORE
Q (IMAG) DIN
Q
[n] DOUT
Q
[n]
+
+
ADC A
CORE
I (REAL) 0 TO 47
DELAY TAPS
48-TAP FIR
FILTER
xy
I
[n]
48-TAP FIR
FILTER
xy
Q
[n]
DIN
I
[n] DOUT
I
[n] I′ (REAL)
PROGRAMMABLE FILTER (PFILT)
Q′ (IMAG)
SIGNAL
PROCESSING
BLOCKS
JESD204B
INTERFACE
15550-277
Figure 107. 48-Tap Half Complex Filter Configuration
ADC B
CORE
Q (IMAG)
DIN
Q
[n]
DOUT
Q
[n]
+
+
+
+
ADC A
CORE
I (REAL) 24-TAP FIR
FILTER
x
I
[n]
24-TAP FIR
FILTER
y
I
[n]
24-TAP FIR
FILTER
y
Q
[n]
24-TAP FIR
FILTER
x
Q
[n]
DIN
I
[n] DOUT
I
[n] I′ (REAL)
PROGRAMMABLE FILTER (PFILT)
Q′ (IMAG)
SIGNAL
PROCESSING
BLOCKS
JESD204B
INTERFACE
15550-278
Figure 108. 24-Tap Full Complex Filter Configuration.
AD9689 Data Sheet
Rev. A | Page 42 of 134
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 0x0E7F (see Table 14 and Table 15).
c. Program the YI coefficients in Register 0x0F00 to
Register 0x0E7F (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 0x0E7F (see Table 14 and Table 15).
d. Program the YQ coefficients in Register 0x0F00 to
Register 0x0E7F (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 by setting 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
Channel A or Channel B (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 in Q1.15 format (sign bit plus 15 fractional bits).
Data Sheet AD9689
Rev. A | Page 43 of 134
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.
AD9689 Data Sheet
Rev. A | Page 44 of 134
DIGITAL DOWNCONVERTER (DDC)
The AD9689 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 AD9689 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 48 and Table 50 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
DDCx complex to real enable bit, Bit 3, in the DDCx 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 126.
DDC GENERAL DESCRIPTION
The four DDC blocks 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 109 shows the detailed block diagram of the DDCs
implemented in the AD9689.
Figure 110 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 AD9689
Rev. A | Page 45 of 134
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
15550-053
Figure 109. DDC Detailed Block Diagram
AD9689 Data Sheet
Rev. A | Page 46 of 134
cos(ωt)
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
HALF-
BAND
FILTER
HB1 FIR
QQ
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(ωt)
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)
15550-054
Figure 110. DDC Theory of Operation Example (Real Input)
Data Sheet AD9689
Rev. A | Page 47 of 134
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 DDCx 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 variable IF 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 ZIF mode, the mixers are bypassed, and the NCO is disabled.
fS/4 Hz IF Mode
In fS/4 Hz IF mode, the mixers and the NCO are enabled in
downmixing by fS/4 mode to save power.
Test Mode
In test 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 111 and Figure 112 show examples of the frequency
translation stage for both real and complex inputs, respectively.
BANDWIDTH OF
INTEREST
BANDWIDTH OF
INTEREST IMAGE
NCO FREQUENCY TUNING WORD (FTW) SELECTION
48-BIT NCO FTW = MIXING FREQUENCY/ADC SAMPLE RATE × 2
48
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(ωt)
0°
90°
I
Q
ADC
SAMPLING
AT
f
S
REAL REAL
–sin(ωt)
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)
15550-055
Figure 111. DDC NCO Frequency Tuning Word Selection—Real Inputs
AD9689 Data Sheet
Rev. A | Page 48 of 134
NCO FREQUENCY TUNING WORD (FTW) SELECTION
48-BIT NCO FTW = MIXING FREQUENCY/ADC SAMPLE RATE × 248
QUADRATURE ANALOG MIXER +
2 ADCs + QUADRATURE DIGITAL
MIXER + NCO
COMPLEX INPUT—SAMPLED AT fS
–fS/32 fS/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(ωt)
ADC
SAMPLING
AT fS
ADC
SAMPLING
AT fS
90°
PHASE
48-BIT
NCO
90°
0°
48-BIT NCO FTW =
ROUND ((fS/3)/fS × 248) = +9.382513
(0x5555_5555_5555)
–fS/2 –fS/3 –fS/4 –fS/8 fS/16 fS/8 fS/4 fS/3 fS/2–fS/16
–fS/32 fS/32
DC
15550-056
Figure 112. DDC NCO Frequency Tuning Word Selection—Complex Inputs
Data Sheet AD9689
Rev. A | Page 49 of 134
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
additional modes.
DDC NCO Programmable Modulus Mode
DDC NCO programmable modulus 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
DDC NCO coherent 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 113 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 113 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
15550-283
Figure 113. NCO + Mixer Block Diagram
AD9689 Data Sheet
Rev. A | Page 50 of 134
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
N C O FT W.
M AW 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 2600 MSPS
and the carrier frequency (fC) is 1001.5 MHz, then
5200
2003
2600
)2600,5.1001mod( ==
N
M
3590F68C0x629B
2600
)2600,5.1001mod(
2floor
48
=
=FTW
MAW = mod(248 × 2003, 5200) = 0x0000 0000 0300
MBW = 0x0000 0000 1450
The actual carrier frequency (fC_ACTUAL) 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
MHz
5.1001
2
145000000x0000
030000000x0000
3590F68C0x629B
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 AD9689
Rev. A | Page 51 of 134
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:
=
s
sc
f
ff
FTW ),mod(
2round 48
(5)
where:
FTW is the 48-bit twos complement number representing the
NCO F T W.
fC is the desired carrier frequency.
fS is the ADC sampling 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 2600 MSPS
and the carrier frequency (fC) is 416.667 MHz, then
A997928F0x2906
2600
)2600,667.416mod(
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
2600667
.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 113). These shadow registers are
hereafter referred to as the NCO channels.
Figure 114 shows a simplified block diagram of the NCO
channel selection block. The gray lines in Figure 114 represent
SPI control lines.
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, as
described in the following sections.
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
15550-284
Figure 114. NCO Channel Selection Block
AD9689 Data Sheet
Rev. A | Page 52 of 134
GPIO Level Control Mode
The GPIO pins determine the exact NCO channel selected.
The following procedure must be followed to use GPIO level
control for NCO channel selection:
1. Configure one or more GPIO pins as NCO channel
selection inputs. GPIO pins not configured as NCO
channel selection 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.
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 ordering.
3. Select the desired NCO channel through the GPIO pins.
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 the DDC soft reset.
The following procedure must be followed to use GPIO edge
control 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.
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 (0, 1, 2, 3, 4, 0, 1, 2, 3, 4, and so on).
4. Transition the selected GPIO pin from low to high to
increment the NCO channel selection.
Register Map Mode
NCO channel selection is controlled directly through the
register map.
Figure 115 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.
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 all 16 channels can be used to queue the next hop.
After SYSREF± synchronization at startup, all NCOs across
multiple chips are inherently synchronized.
fS
/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
f0f1f2
ACTIVE
DDC
15550-285
Figure 115. NCO Coherent Mode with Three NCO Channels (B0 Selected)
Data Sheet AD9689
Rev. A | Page 53 of 134
Setting Up the Multichannel NCO Feature
The first step to configure the multichannel NCO is to program
the FTWs. The AD9689 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
calculated using the PAW, FTW, MAW, MBW, and POW. Due to
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 is likely to need 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 AD9689 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.
AD9689 Data Sheet
Rev. A | Page 54 of 134
The synchronization triggering mechanism uses a master/slave
arrangement, as shown in Figure 116.
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)
15550-286
Figure 116. 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 47 (Register 0x0041 and Register 0x0042) to configure
the FD_x/GPIO pins for this operation.
NCO Multichip Synchronization at Startup
Figure 117 shows a timing diagram along with the required
sequence of events for NCO multichip synchronization using
triggering and SYSREF at startup. Using this start-up 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
15550-287
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
Figure 117. NCO Multichip Synchronization at Startup (Using Triggering and SYSREF)
Data Sheet AD9689
Rev. A | Page 55 of 134
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 118 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 shows 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
pass-band ripple and >100 dB of stop band alias rejection.
DECIMATION FILTERS DCM = 3
FIR = FI NIT E I M PULSE RESPONSE FI LTER
DCM = DECIMATIO N
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 O N LY S U P P ORTED I N DDC0 AND DDC1
GAIN = 0dB OR +6dB
COMPLEX TO REAL CONVERSION
(OPTIONAL)
15550-288
Figure 118. DDC Decimation Filter Block Diagram
AD9689 Data Sheet
Rev. A | Page 56 of 134
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
TB1 1 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 Configurations 1
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
f
S
HB1
1
f
S
2
f
S
/2 (I) + f
S
/2 (Q)
f
S
/2 × 80%
1
TB1 3 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 + TB1
3
N/A
N/A
30
f
S
/30 (I) + f
S
/30 (Q)
f
S
/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 DDC0 and DDC1.
Data Sheet AD9689
Rev. A | Page 57 of 134
HB4 Filter Description
The first decimate by 2, half-band, low-pass, FIR filter (HB4)
uses an 11-tap, symmetrical, fixed coefficient filter impleme-
ntation 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 18 and Figure 119 show the coefficients and
response of the HB4 filter.
Table 18. 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 0.293335 4806
C6 0.5 8192
–160
–140
–120
–100
–80
–60
–40
–20
0
20
00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
MAGNITUDE (dB)
NORMALIZED FREQUENCY (× Π RAD/s)
15550-289
Figure 119. 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 19 and Figure 120 show the coefficients and
response of the HB3 filter.
Table 19. HB3 Filter Coefficients
HB3 Coefficient
Number
Normalized
Coefficient
Decimal Coefficient
(17-Bit)
C1, C11 0.006638 435
C2, C10 0 0
C3, C9
−0.051056
−3346
C4, C8 0 0
C5, C7 0.294418 19295
C6 0.500000 32768
–160
–140
–120
–100
–80
–60
–40
–20
0
20
00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
MAGNITUDE (dB)
NORMALIZED FREQUENCY (× Π RAD/s)
15550-290
Figure 120. 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) are enabled; otherwise, it is bypassed.
Table 20 and Figure 121 show the coefficients and response of
the HB2 filter.
Table 20. 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 −0.074181 −9723
C8, C12 0 0
C9, C11 0.306091 40120
C10 0.5 65536
–160
–140
–120
–100
–80
–60
–40
–20
0
20
00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
MAGNITUDE (dB)
NORMALIZED FREQUENCY (× Π RAD/s)
15550-291
Figure 121. HB2 Filter Response
AD9689 Data Sheet
Rev. A | Page 58 of 134
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 21 and Figure 122 show the coefficients and response of
the HB1 filter.
Table 21. 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
−0.002840
−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 0.024420 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
00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
MAGNITUDE (dB)
NORMALIZED FREQUENCY (× Π RAD/s)
15550-292
Figure 122. HB1 Filter Response
TB2 Filter Description
The TB2 filter 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 22 and Figure 123 show the coefficients
and response of the TB2 filter.
Table 22. TB2 Filter Coefficients
TB2 Coefficient
Number
Normalized
Coefficient
Decimal Coefficient
(19-Bit)
C1, C26 −0.000191 −50
C2, C25 −0.000793 −208
C3, C24 −0.001137 −298
C4, C23 0.000916 240
C5, C22 0.006290 1649
C6, C21 0.009823 2575
C7, C20 0.000916 240
C8, C19 −0.023483 −6156
C9, C18 −0.043152 −11312
C10, C17 −0.019318 −5064
C11, C16
0.071327
18698
C12, C15 0.201172 52736
C13, C14 0.297756 78055
–160
–140
–120
–100
–80
–60
–40
–20
0
20
00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
MAGNITUDE (dB)
NORMALIZED FREQUENCY (× Π RAD/s)
15550-293
Figure 123. TB2 Filter Response
Data Sheet AD9689
Rev. A | Page 59 of 134
TB1 Filter Description
The TB1 decimate by 3, low-pass, FIR filter uses a 76-tap,
symmetrical, fixed coefficient filter implementation. Table 23
shows the TB1 filter coefficients, and Figure 124 shows the TB1
filter response. TB1 is only supported in DDC0 and DDC1.
Table 23. TB1 Filter Coefficients
TB1 Coefficient
Number
Normalized
Coefficient
Decimal 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 (× Π RAD/s)
–160
–140
–120
–100
–80
–60
–40
–20
0
20
00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
15550-294
Figure 124. TB1 Filter Response
AD9689 Data Sheet
Rev. A | Page 60 of 134
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 125 shows the FB2
filter response.
Table 24. FB2 Filter Coefficients
FB2 Coefficient
Number
Normalized
Coefficient
Decimal 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
00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
MAGNITUDE (dB)
NORMALIZED FREQUENCY (× Π RAD/s)
15550-295
Figure 125. FB2 Filter Response
Data Sheet AD9689
Rev. A | Page 61 of 134
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 126 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(ωt)
sin(ωt)
I/REAL
0dB
OR
6dB
0dB
OR
6dB
0dB
OR
6dB
0dB
OR
6dB
f
S
/4
15550-057
Figure 126. Complex to Real Conversion Block
AD9689 Data Sheet
Rev. A | Page 62 of 134
DDC MIXED DECIMATION SETTINGS
The AD9689 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 25 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 26.
Table 25. 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 AD9689
Rev. A | Page 63 of 134
Table 26. 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.
AD9689 Data Sheet
Rev. A | Page 64 of 134
DDC EXAMPLE CONFIGURATIONS
Table 27 describes the register settings for multiple DDC example configurations.
Table 27. DDC Example Configurations (Per ADC Channel Pair)
Chip
Application
Layer
Chip
Decimation
Ratio
DDC
Input
Type
DDC
Output
Type
Bandwidth
Per DDC 1
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
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
Data Sheet AD9689
Rev. A | Page 65 of 134
Chip
Application
Layer
Chip
Decimation
Ratio
DDC
Input
Type
DDC
Output
Type
Bandwidth
Per DDC 1
No. of Virtual
Converters
Required Register Settings
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
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
AD9689 Data Sheet
Rev. A | Page 66 of 134
Chip
Application
Layer
Chip
Decimation
Ratio
DDC
Input
Type
DDC
Output
Type
Bandwidth
Per DDC 1
No. of Virtual
Converters
Required Register Settings
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
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 AD9689
Rev. A | Page 67 of 134
DDC POWER CONSUMPTION
Table 28 and Figure 28 describe the typical and maximum DVDD and DRVDD1 power consumption for certain DDC modes for 2.0 GSPS
and 2.6 GSPS.
Table 28. DDC Power Consumption for Example Configurations for 2.0 GSPS; fS = 2.0 GHz
Number of
DDCs
DDC Decimation
Ratio 1
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 3 8 4 2 465 958 240 345
2 4 8 4 1 400 877 200 301
2 6 4 4 2 405 881 135 226
2 8 4 4 2 385 858 115 205
2 12 2 4 4 400 870 80 170
4
6
8
8
2
525
1040
240
345
4 8 8 8 2 485 970 200 295
1 See Table 17 for details on decimation filter selection, the associated alias protected bandwidths, and SNR improvements.
Table 29. DDC Power Consumption for Example Configurations for 2.6 GSPS; fS = 2.56 GHz
Number of
DDCs
DDC Decimation
Ratio 1
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 3 8 4 2 575 995 280 375
2 4 8 4 1 520 930 230 325
2 6 4 4 2 515 925 155 238
2 8 4 4 2 500 905 135 211
2 12 2 4 4 510 912 95 165
4 6 8 8 2 655 1090 280 380
4 8 8 8 2 630 1090 230 325
1 See Table 17 for details on decimation filter selection, the associated alias protected bandwidths, and SNR improvements.
AD9689 Data Sheet
Rev. A | Page 68 of 134
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 127
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
15550-049
Figure 127. 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 updates in the magnitude storage register, and the
comparison and update procedure, as explained previously,
continues.
Data Sheet AD9689
Rev. A | Page 69 of 134
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 128 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 128). To select the SPORT
over JESD204B option, program Register 0x0559,
Register 0x055A, and Register 0x058F. See Table 51 for more
information on setting these registers.
Figure 129 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 130 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)
14 13 12 11 10 9876543210
15 14 13 12 11 10 9876543210
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)
15550-050
Figure 128. 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] 0 0 0
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
15550-051
Figure 129. SPORT over JESD204B Signal Monitor Frame Data
AD9689 Data Sheet
Rev. A | Page 70 of 134
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 IDLE
IDENT. DATA
MSB DATA DATA DATA
LSB
IDLE IDLE IDLE IDLE IDLE IDLEIDLE IDLE IDLE IDLE IDLE
IDENT. 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
15550-052
Figure 130. SPORT over JESD204B Signal Monitor Example with Period = 80 Samples
Data Sheet AD9689
Rev. A | Page 71 of 134
DIGITAL OUTPUTS
INTRODUCTION TO THE JESD204B INTERFACE
The AD9689 digital outputs are designed to the JEDEC standard
JESD204B, serial interface for data converters. JESD204B is a
protocol to link the AD9689 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 AD9689 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 AD9689
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); AD9689 value = 1, 2, 4, or 8.
• M is the number of converters per converter device (virtual
converters per link); AD9689 value = 1, 2, 4, or 8.
• F is the octets per frame; AD9689 value = 1, 2, 4, 8, or 16.
• N΄ is the number of bits per sample (JESD204B word size);
AD9689 value = 8 or 16.
• N is the converter resolution; AD9689 value = 7 to 16.
• CS is the number of control bits per sample;
AD9689 value = 0, 1, 2, or 3.
• K is the number of frames per multiframe;
AD9689 value = 4, 8, 12, 16, 20, 24, 28, or 32.
• S is the samples transmitted per single converter per frame
cycle; AD9689 value is set automatically based on L, M, F,
and N΄.
• HD is the high density mode; the AD9689 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; AD9689 value = 0.
Figure 131 shows a simplified block diagram of the AD9689
JESD204B link. By default, the AD9689 is configured to use
two converters and eight lanes. Converter A data is output to
SERDOUT0±, SERDOUT1±, SERDOUT2± and SERDOUT3±;
and Converter B is output to SERDOUT4±, SERDOUT5±,
SERDOUT6±, and SERDOUT7±. The AD9689 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 the SPI
register map, along with additional customizable options.
By default in the AD9689, 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 132 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 132 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
15550-058
Figure 131. Transmit Link Simplified Block Diagram Showing Full Bandwidth Mode (Register 0x0200 = 0x00)
AD9689 Data Sheet
Rev. A | Page 72 of 134
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]
A13
MSB
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
C1
CONTROL 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
abijab i j
abcdefghij
abcdef g h i j
S6
S5
S4
S3
S2
S1
S0
MSB
LSB
8-BIT/
10-BIT
ENCODER
OCTET0
OCTET1
15550-059
Figure 132. 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
15550-060
Figure 133. Data Flow
FUNCTIONAL OVERVIEW
The block diagram in Figure 133 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, four, or eight lanes of high speed differential serial data.
JESD204B LINK ESTABLISHMENT
The AD9689 JESD204B transmitter (Tx) interface operates in
Subclass 1 as defined in the JEDEC Standard JESD204B
(July 2011 specification). The link establishment process is
divided into the following steps: code group synchronization
(CGS) and SYNCINB±, initial lane alignment sequence, and user
data and error correction.
CGS and SYNCINB±
CGS is the process in 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 AD9689 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 AD9689 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 AD9689
Rev. A | Page 73 of 134
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 P13
(SYNCINB−) floating.
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 134. 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 completes, the user
data is sent. Normally, within a frame, all characters are considered
to be 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, and 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.
KKRD
START OF
ILAS
●●●DARQD A R D D A R D D
END OF
MULTIFRAME
A DC C D
START OF LINK
CONFIGURATION DATA
START OF
USER DATA
●●● ●●● ●●●●●●
●●● ●●● ●●● ●●●●●●
15550-061
Figure 134. Initial Lane Alignment Sequence
Table 30. AD9689 Control Characters Used in JESD204B
Abbreviation Control Symbol 8-Bit Value 10-Bit Value, RD = −1 10-Bit Value, RD = +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.
AD9689 Data Sheet
Rev. A | Page 74 of 134
SERDOUTx+
DRVDD
SERDOUTx–
OUTPUT SWING = 0.85 × DRVDD1 V p-p DIFFERENTIAL
ADJUSTABLE TO
1 × DRVDD1, 0.75 × DRVDD1
100Ω
0.1µF
0.1µF RECEIVER
100Ω
DIFFERENTIAL
TRACE PAIR
15550-063
Figure 135. AC-Coupled Digital Output Termination Example
PHYSICAL LAYER (DRIVER) OUTPUTS
Digital Outputs, Timing, and Controls
The AD9689 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 Ω 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 135). 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 51) for more details.
The AD9689 digital outputs can interface with custom
application specific integrated circuits (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 Ω 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 136 to Figure 138 show an example of the digital output
data eye, jitter histogram, and bathtub curve for one AD9689
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 51).
15550-306
Figure 136. Digital Outputs Data Eye, External 100 Ω Terminations at 16 Gbps
15550-307
Figure 137. Digital Outputs Jitter Histogram, External 100 Ω Terminations at
16 Gbps
15550-308
Figure 138. 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 51) 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 LOL 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 AD9689 using Register 0x056E.
Data Sheet AD9689
Rev. A | Page 75 of 134
Table 31. AD9689 Register 0x056E Supported Lane Rates
Value Lane Rate
0x00 Lane rate = 6.75 Gbps to 13.5 Gbps (default for AD9689)
0x10 Lane rate = 3.375 Gbps to 6.75 Gbps
0x30 Lane rate = 13.5 Gbps to 16 Gbps
0x50 Lane rate = 1.6875 Gbps to 3.375 Gbps
fS × 4 MODE
fS × 4 mode adds a separate packing mode to a JESD204B
transmitter/receiver to set 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 139,
and the receive portion is shown in Figure 140. 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)
APPLICATION
LAYER
TRANSPORT,
DATA LINK,
AND PHY
LAYERS
12 BITS
AT
fS
LANE 0 LANE 1 LANE 2 LANE 3 LANE 4 LANE 5 LANE 6 LANE 7
fS
× 4 MODE (TRANSMIT)
1/5 RATE EXCHANGE
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
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
15550-309
Figure 139. fS × 4 Mode (Transmit)
AD9689 Data Sheet
Rev. A | Page 76 of 134
f
S
× 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
15550-310
Figure 140. fS × 4 Mode (Receive)
SETTING UP THE AD9689 DIGITAL INTERFACE
To ensure proper operation of the AD9689 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. AD9689 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 AD9689 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 102.
The maximum lane rate allowed by the AD9689 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
f
CLOCKADC _
The decimation ratio (DCM) is the parameter programmed in
Register 0x0201.
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 35 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.
Data Sheet AD9689
Rev. A | Page 77 of 134
Table 33. JESD204B Output Configurations for N΄ = 1637F
1
Number
of Virtual
Converters
Supported
(Same as M)
JESD204B
Serial
Lane
Rate38F
2
Supported Decimation Rates
JESD204B Transport Layer Settings39F
3
Lane Rate =
1.6875 Gbps to
3.375 Gbps
Lane Rate =
3.375 Gbps to
6.75 Gbps
Lane Rate =
6.75 Gbps to
13.5 Gbps
Lane Rate =
13.5 Gbps to
16 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 40F4
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
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
AD9689 Data Sheet
Rev. A | Page 78 of 134
Number
of Virtual
Converters
Supported
(Same as M)
JESD204B
Serial
Lane
Rate38F
2
Supported Decimation Rates
JESD204B Transport Layer Settings39F
3
Lane Rate =
1.6875 Gbps to
3.375 Gbps
Lane Rate =
3.375 Gbps to
6.75 Gbps
Lane Rate =
6.75 Gbps to
13.5 Gbps
Lane Rate =
13.5 Gbps to
16 Gbps L M F S HD N N' CS K
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 ≤16000 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.
Data Sheet AD9689
Rev. A | Page 79 of 134
Table 34. JESD204B Output Configurations (N' = 12)41F
1
Supported Decimation Rates
No. of Virtual
Converters
Supported
(Same Value as M)
Serial
Lane
Rate42F
2
Lane Rate =
1.6875 Gbps
to 3.375 Gbps
Lane Rate =
3.375 Gbps to
6.75 Gbps
Lane Rate =
6.75 Gbps to
13.5 Gbps
Lane Rate =
13.5 Gbps to
16 Gbps
JESD204B Transport Layer Settings43F
3
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 44F4
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 ≤16000 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.
AD9689 Data Sheet
Rev. A | Page 80 of 134
Table 35. JESD204B Output Congurations for N΄ = 845F
1
Supported Decimation Rates
No. of Virtual
Converters
Supported
(Same Value as M)
Serial
Lane
Rate46F
2
Lane Rate =
1.6875 Gbps to
3.375 Gbps
Lane Rate =
3.375 Gbps to
6.75 Gbps
Lane Rate =
6.75 Gbps to
13.5 Gbps
Lane Rate =
13.5 Gbps to
16 Gbps
JESD204B Transport Layer Settings47F
3
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 48F4
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 ≤16000 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 AD9689
Rev. A | Page 81 of 134
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~
2560MSPS 12.8Gbps/LANE
F = 1
M
1
14-BIT
ADC
CORE
14-BIT
ADC
CORE
15550-311
Figure 141. Full Bandwidth Mode
The AD9689 is set up as shown in Figure 141, with the following
configurations:
• Two 14-bit converters at 2.56 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) = 2560/1 = 2560 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 = 12.8 Gbps per lane.
• The PLL control register, Register 0x056E, is set to 0x00.
Set up the AD9689 in this mode using the following sequence:
1. Write 0x81 to Register 0x0000 (SPI soft reset).
2. Wait 5 ms to 10 ms.
3. Write 0x00 to Register 0x0200 (full bandwidth mode).
4. Write 0x00 to Register 0x0201 (chip decimation ratio = 1).
5. Write 0x15 to Register 0x0571 (JESD204B link power-
down).
6. Write 0x87 to Register 0x058B (scrambling enabled, L = 8).
7. Write 0x01 to Register 0x058E (M = 2).
8. Write0x00 to Register 0x058C (F = 1).
9. Write 0x00 to Register 0x056E (lane rate = 6.75 Gbps to
13.5 Gbps).
10. Write 0x14 to Register 0x0571 (JESD204B link power-up).
11. Wait 5 ms to 10 ms.
12. Read Register 0x056F (PLL status register).
13. Write 0x4F to Register 0x1228.
14. Write 0x0F to Register 0x1228.
15. Write 0x00 to Register 0x1222.
16. Write 0x04 to Register 0x1222.
17. Write 0x00 to Register 0x1222.
18. Write 0x08 to Register 0x1262.
19. Write 0x00 to Register 0x1262.
AD9689 Data Sheet
Rev. A | Page 82 of 134
Example 2—ADC with DDC Option (Two ADCs Plus Two DDCs)
40 × fOUT MbPS
fOUT = fS/10 (MHz)fS (MHz)
F = 4
14-BIT
ADC CORE
DDC 1
(REAL INPUT,
DCM = 10
C2R = BYPASS) M3(Q)
M2(I)
VIN_B
REAL
14-BIT
ADC CORE
DDC 0
(REAL INPUT,
DCM = 10
C2R = BYPASS)
JESD204B LINK
(L = 2 M = 4 F = 4,
S = 1, N’ = 16, N = 16,
CS = 0, HD = 0)
M1(Q)
M0(I)
LAB0
LAB1
SYNC~
VIN_A
REAL
M0(I)S0[15:8]
M0(I)S0[7:0]
M1(Q)S0[15:8]
M1(Q)S0[7:0]
M2(I)S0[15:8]
M2(I)S0[7:0]
M3(Q)S0[15:8]
M3(Q)S0[7:0]
I = REAL COMPONENT
Q = QUADRATURE COMPONENT
DCM = DECIMATION
C2R = COMPLEX TO REAL
MX = VIRTUAL CONVERTER X
LY = LANE Y
SZ = SAMPLE Z INSIDE A JESD204B FRAME
C = CONTROL BIT (OVER RANGE, AMONG OTHERS)
T = TAIL BIT
15550-312
Figure 142. Two ADCs Plus Two DDCs Mode (L = 2, M = 4, F = 4, S = 1)
This example shows the flexibility in the digital and lane
configurations for the AD9689. The sample rate is 2.4576 GSPS,
whereas the outputs are all combined in a combination of either
two, four, or eight lanes, depending on the input/output speed
capability of the receiving device.
The AD9689 is set up as shown in Figure 142, with the following
configuration:
• Two 14-bit converters at 2.4576 GSPS.
• Two DDC application layer mode with complex outputs (I/Q).
• Chip decimation ratio = 10.
• DDC decimation ratio = 10 (see Table 33).
The JESD204B output configuration is as follows:
• Four virtual converters required (see Table 33).
• Output sample rate (fOUT) = 2457.6/10 = 245.76 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 = 9.8304 Gbps per lane (L = 2),
4.9152 Gbps per lane (L = 4), or 2.4576 Gbps per lane (L = 8).
For L = 2, set the PLL control register, Register 0x056E, to 0x00.
For L = 4, set the PLL control register, Register 0x056E, to 0x10.
For L = 8, set the PLL control register, Register 0x056E, to 0x50.
Set up the AD9689 in this mode using the following sequence:
1. Write 0x81 to Register 0x0000 (SPI soft reset).
2. Wait 5 ms to 10 ms.
3. Write 0x02 to Register 0x0200 (two DDC mode).
4. Write 0x06 to Register 0x0201 (chip decimation ratio = 10).
5. Write 0x47 to Register 0x0310 (6 dB gain, decimation ratio
set by Register 0x0311, Bits[7:4]).
6. Write 0x20 to Register 0x0311 (decimate by 10, DDC0
inputs from Channel A).
7. Register 0x0316 to Register 0x031B is the DDC0 NCO
tuning word.
8. Write 0x47 to Register 0x0330 (6 dB gain, decimation ratio
set by Register 0x0331, Bits[7:4]).
9. Write 0x25 to Register 0x0331 (decimate by 10, DDC1
inputs from Channel B).
10. Register 0x0336 to Register 0x033B is the DDC0 NCO
tuning word.
11. Write 0x15 to Register 0x0571 (JESD204B link power down).
12. Write 0x81 to Register 0x058B (scrambling enabled, L = 2).
13. Write 0x03 to Register 0x058E (M = 4).
14. Write 0x03 to Register 0x058C (F = 4).
15. Write 0x00 to Register 0x056E (lane rate = 6.75 Gbps to
13.5 Gbps).
16. Write 0x14 to Register 0x0571 (JESD204B link power up).
17. Wait 5 ms to 10 ms.
18. Read Register 0x056F (PLL status register).
19. Write 0x4F to Register 0x1228.
20. Write 0x0F to Register 0x1228.
21. Write 0x00 to Register 0x1222.
22. Write 0x04 to Register 0x1222.
23. Write 0x00 to Register 0x1222.
24. Write 0x08 to Register 0x1262.
25. Write 0x00 to Register 0x1262.
Data Sheet AD9689
Rev. A | Page 83 of 134
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 AD9689 supports JESD204B Subclass 0 and Subclass 1
operation. Register 0x0590, Bits[7:5] set the subclass mode for the
AD9689 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 AD9689 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
decimal), 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 signal
synchronizes the LMFCs for each device in a link or across
multiple links (within the AD9689, SYSREF also synchronizes
the internal sample dividers), as shown in Figure 143. The
JESD204B receiver uses the multiframe boundaries and
buffering to achieve consistent latency across lanes (or even
multiple devices), and 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 143). 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 <
t
LMFC)
15550-313
Figure 143. SYSREF and LMFC
AD9689 Data Sheet
Rev. A | Page 84 of 134
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 AD9689 using the LMFC offset register
(Register 0x0578, Bits[4:0]). This adjustment 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 144
shows that, when the link latency is near an LMFC boundary,
the local LMFC of the AD9689 can be adjusted to delay the data
arrival time at the receiver. Figure 145 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 AD9689 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 status bits (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, a few adjustments can be made in the AD9689.
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
15550-314
Figure 144. Adjusting the JESD204B Tx LMFC in the AD9689
DATA
POWER CYCLE VARIATIONLMFC
RX
DELAY TIME
ILAS ILAS
ILAS
SYSREF 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
DATA
15550-315
Figure 145. Adjusting the JESD204B Rx LMFC in the Logic Device
Data Sheet AD9689
Rev. A | Page 85 of 134
MULTICHIP SYNCHRONIZATION
The flowchart in Figure 147 shows the internal mechanism for
multichip synchronization in the AD9689. There are two methods
by which multichip synchronization can take place, as determined
by the 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 AD9689 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 referred to as
normal mode (see Figure 147). Following the process in the
flowchart ensures that the AD9689 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 AD9689 full bandwidth operating modes, the SYSREF
input can also be used to timestamp samples, 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 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 decimal).
• At least one control bit must be enabled (Register 0x058F,
Bits[7:6] = 1, 2, or 3 decimal).
• Set the function for one of the control bits to SYSREF:
Register 0x0559, Bits[3:0] = 5 decimal if using Control Bit
0, Register 0x0559, Bits[7:4] = 5 decimal if using Control
Bit 1, Register 0x055A, Bits[3:0] = 5 decimal if using
Control Bit 2.
Figure 146 shows how the input sample coincident with
SYSREF is timestamped and ultimately output from 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 AD9689
operating modes that use decimation.
A
IN
A
A
IN
B
ENCODE CLK
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 NN + 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 NN + 1 N + 2 N + 300 00 00 0001
15550-316
Figure 146. AD9689 Timestamping Example—CS = 2 (Register 0x058F, Bits[7:6] = 2 Decimal), Control Bit 0 is SYSREF (Register 0x0559, Bits[3:0] = 5 Decimal)
AD9689 Data Sheet
Rev. A | Page 86 of 134
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?
(0x010B)
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)
15550-317
Figure 147. SYSREF Capture Scenarios and Multichip Synchronization
Data Sheet AD9689
Rev. A | Page 87 of 134
SYSREF INPUT
The SYSREF input signal is used as a high accuracy system
reference for deterministic latency and multichip synchro-
nization. The AD9689 accepts a single-shot or periodic input
signal. The SYSREF± mode select bits (Register 0x0120, Bits[2:1])
select the input signal type and arm the SYSREF state machine
when set. If in single (or N) shot mode (Register 0x0120, Bits[2:1]
= 2 decimal), 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 decimal), 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
AD9689 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
AD9689 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 148). The AD9689 has several features
that aid the user 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 AD9689 allows the SYSREF signal to be sampled
using either the rising edge or falling edge of the input clock.
Figure 148, Figure 149, Figure 150, and Figure 151 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 AD9689 is able to ignore N SYSREF events (note that the
SYSREF ignore feature is enabled by setting the SYSREF± mode
select bits (Register 0x0120, Bits[2:1]) to 2'b10, 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 152 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
15550-318
Figure 148. SYSREF Setup and Hold Time Requirements—SYSREF Low to
High Transition Using Rising Edge Clock (Default)
CLK
SYSREF
SYSREF
SAMPLE POINT
HOLD
REQUIREMENT
95ps
SETUP
REQUIREMENT
–65ps
15550-319
Figure 149. 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
15550-320
Figure 150. 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
15550-321
Figure 151. SYSREF High to Low Transition Using Falling Edge Clock Capture
(Register 0x0120, Bit 4 = 1’b1; Register 0x0120, Bit 3 = 1’b1)
AD9689 Data Sheet
Rev. A | Page 88 of 134
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
15550-322
Figure 152. 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
15550-323
Figure 153. SYSREF Skew Window
When in continuous SYSREF mode (Register 0x0120, Bits[2:1] =
1), the AD9689 monitors the placement of the SYSREF leading
edge compared to the internal LMFC. If the SYSREF signal is
captured with a clock edge other than the one that is aligned
with the LMFC, the AD9689 initiates a resynchronization of the
link. Because input clock rates for AD9689 can be up to 4 GHz,
the AD9689 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 AD9689 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 the 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 AD9689, the positive
and negative skew window is controlled by the SYSREF window
negative bits (Register 0x0122, Bits[3:2]) and SYSREF window
positive bits (Register 0x0122, Bits[1:0]). Figure 153 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.
Data Sheet AD9689
Rev. A | Page 89 of 134
SYSREF± SETUP/HOLD WINDOW MONITOR
To ensure a valid SYSREF signal capture, the AD9689 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 154 and Figure 155 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
15550-070
Figure 154. SYSREF± Setup Detector
AD9689 Data Sheet
Rev. A | Page 90 of 134
CLK±
INPUT
SYSREF±
INPUT VALID
REG 0x0128[7:4]
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
15550-071
Figure 155. 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.
Data Sheet AD9689
Rev. A | Page 91 of 134
LATENCY
END TO END TOTAL LATENCY
Total latency in the AD9689 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 37 shows the combined latency through the ADC and
digital signal processor (DSP) for the different chip application
modes supported by the AD9689. Table 38 shows the latency
through the JESD204B block for each application mode based
on the M/L ratio. For Table 37 and Table 38, 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 38.
To determine the total latency, select the appropriate ADC + DSP
latency from Table 37 and add it to the appropriate JESD204B
latency from Table 38. 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 the
LMFC referenced latency to make appropriate deterministic
latency adjustments. If they are required, use the latency values
in Table 37 and Table 38 for the analog in to LMFC and LMFC
to data out latency values.
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.
AD9689 Data Sheet
Rev. A | Page 92 of 134
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 203 3 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
318
4
176
4
90
4
47
4
33
4
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.
Data Sheet AD9689
Rev. A | Page 93 of 134
TEST MODES
ADC TEST MODES
The AD9689 has various test options that aid in the system level
implementation. The AD9689 has ADC test modes that are
available in Register 0x0550. 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 pseudorandom number (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.
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]
A13
MSB
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
C1
CONTROL 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
abijabij
abcdefghij
abcdefghij
S6
S5
S4
S3
S2
S1
S0
MSB
LSB
8-BIT/
10-BIT
ENCODER
OCTET0
OCTET1
15550-059
Figure 156. ADC Output Datapath Showing Test Pattern Injection Points
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 Positive full-scale short 01 1111 1111 1111 Not applicable Not applicable
0011 Negative 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
AD9689 Data Sheet
Rev. A | Page 94 of 134
JESD204B BLOCK TEST MODES
In addition to the ADC pipeline test modes, the AD9689 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 inserted at various points along the output
datapath. These test insertion points are shown in Figure 156.
Table 40 describes the various test modes available in the
JESD204B block. For the AD9689, a transition from test modes
(Register 0x0573 ≠ 0x00) to normal mode (Register 0x0573 =
0x00) requires an SPI soft reset, which is done by writing 0x81
to Register 0x0000 (self cleared).
Transport Layer Sample Test Mode
The transport layer samples are implemented in the AD9689 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 inserted at various points along the data. See Figure 156
for more information on the test insertion points. Register 0x0573,
Bits[5:4] show where these tests are inserted.
Table 41, Table 42, and Table 43 show examples of some of the test
modes when inserted at the JESD204B sample input, physical 10-
bit input, and scrambler 8-bit input. UPx in Table 41 to Table 43
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 insertion 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] = 2'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) % 2
16
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
Data Sheet AD9689
Rev. A | Page 95 of 134
Table 42. Physical Layer 10-Bit Input (Register 0x0573, Bits[5:4] = 2'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] = 2'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) % 2
8
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 AD9689
as defined by Section 5.3.3.8.2 in the JEDEC JESD204B speci-
fication. 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.
AD9689 Data Sheet
Rev. A | Page 96 of 134
SERIAL PORT INTERFACE
The AD9689 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 AD9689 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
AD9689. 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.
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 AD9689 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 AD9689
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.
Serializer/Deserializer (SERDES) Output Setup Allows the user to vary SERDES settings such as swing and emphasis.
Data Sheet AD9689
Rev. A | Page 97 of 134
MEMORY MAP
READING THE MEMORY MAP REGISTER TABLE
Each address 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 0x01FF)
• Chip operating mode control registers (Register 0x0200 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 and Register 0x1222 to Register 0x01262)
• Programmable filter control and coefficients registers
(Register 0x0DF8 to Register 0x0F7F)
• VREF/analog input control registers (Register 0x18A6 to
Register 0x1A4D and Register 0x0701 to Register 0x073B)
The Memory Map Register Details section documents the default
hexadecimal value for each hexadecimal address shown. 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 46 to Table 53.
Open and Reserved Locations
All address and bit locations that are not included in Table 46 to
Table 53 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 AD9689 is reset, critical registers are loaded with
default values. The default values for the registers are given in
the memory map register tables, Table 46 to Table 53.
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 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. All other registers and bits are considered global,
and changes to these registers and bits 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 AD9689 requires 5 ms to recover. When programming the
AD9689 for application setup, ensure that an adequate delay is
programmed into the firmware after asserting the soft reset and
before starting the device setup.
AD9689 Data Sheet
Rev. A | Page 98 of 134
MEMORY MAP REGISTER DETAILS
All address locations that are not included in Table 46 to Table 53 are not currently supported for this device and must not be written.
Analog Devices SPI Registers
Table 46.
Addr. Name Bit(s) Bit Name Setting Description Reset Access
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, to provide 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 shifted first for all SPI operations.
0 Most significant bit shifted first for all SPI operations.
5 Address ascension mirror 0x0 R/W
0 Multibyte SPI operations cause addresses to auto-decrement.
1 Multibyte SPI operations cause addresses to auto-increment.
[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 Least significant bit shifted first for all SPI operations.
0
Most significant bit 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, to provide 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
0xD9
AD9689.
0x0005 Chip ID MSB [7:0] Chip ID MSB[15:8] Chip ID. 0x0 R
0x0006 Chip grade [7:4] Chip speed grade Chip speed grade. 0x0 R
0x0
2.6 GSPS.
0x1
2.0 GSPS.
[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.
Data Sheet AD9689
Rev. A | Page 99 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
0x000A Scratch pad [7:0] Scratch pad Chip scratch pad register. This register is used to provide a
consistent memory location for software debug.
0x0 R/W
0x000B SPI revision [7:0] SPI revision SPI revision register. 0x01: Revision 1.0. 0x1 R
00000001
Revision 1.0.
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 FTW/POW/MAW/MBW increment and phase offset
registers when DDC phase update mode (Register 0x0300, Bit
7) = 1, which 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 Power-Down Pin Control Registers
Table 47.
Addr. Name Bit(s) Bit Name Setting Description Reset Access
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] 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 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 Register 0x0041, Bits[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).
AD9689 Data Sheet
Rev. A | Page 100 of 134
Addr. Name Bit(s) Bit Name Setting 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 auto phase adjust enable. When enabled,
Register 0x0129, Bits[3:0] contain the phase of the divider when
SYSREF was captured. 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].
The skew 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
00 No negative skew; SYSREF must be captured accurately.
01 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]. The
skew 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
00 No positive skew; SYSREF must be captured accurately.
01 ½ device clock of positive skew.
10 1 device clocks of positive skew.
11 1½ device clocks of positive skew.
Data Sheet AD9689
Rev. A | Page 101 of 134
Addr. Name Bit(s) Bit Name Setting 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 Register 0x010A, Bit 7 = 1. When
Register 0x010A, Bit 7 = 1 and Register 0x010A, Bits[3:2] = 0
decimal and Register 0x010A, Bits[1:0] = 0 decimal, 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); super fine
delay enabled (all 128 delay steps are valid).
0x0111 Clock super fine
delay (local)
[7:0] Clock super fine delay
adjust
Clock super fine delay adjust. This is an unsigned control to
adjust the super fine 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 is 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.
AD9689 Data Sheet
Rev. A | Page 102 of 134
Addr. Name Bit(s) Bit Name Setting 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/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
00 Captured on the rising edge of CLK± input.
01 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± transition 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
Data Sheet AD9689
Rev. A | Page 103 of 134
Addr. Name Bit(s) Bit Name Setting 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 0x0120, Bit 6. Wraps
around at 255. Read these bits only when Register 0x0120, 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 when it passes through the ADC
and is used as a control bit in the JESD204B output word.
Chip Operating Mode Control Registers
Table 48.
Addr. Name Bit(s) Bit Name Setting Description Reset Access
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.
AD9689 Data Sheet
Rev. A | Page 104 of 134
Fast Detect and Signal Monitor Control Registers
Table 49.
Addr. Name Bit(s) Bit Name Setting Description Reset Access
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 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
LSBs of 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 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
LSBs of 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 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 LSBs of 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 has been captured, Register 0x026F, Bit 0 is cleared.
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
Data Sheet AD9689
Rev. A | Page 105 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
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
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[7:0] Signal monitor frame counter status bits. The 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)
Table 50.
Addr. Name Bit(s) Bit Name Setting Description Reset Access
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
AD9689 Data Sheet
Rev. A | Page 106 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
1 DDC next sync 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 mode 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 Synchronization enabled. If 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].
Data Sheet AD9689
Rev. A | Page 107 of 134
Addr. Name Bit(s) Bit Name Setting 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
0000 TB2 + HB4 + HB3 + HB2 + HB1 filter selection: decimate by 48
(complex to real disabled), or decimate by 24 (complex to real
enabled).
0010 FB2 + HB1 filter selection: decimate by 10 (complex to real
disabled), or decimate by 5 (complex to real enabled).
0011 FB2 + HB2 + HB1 filter selection: decimate by 20 (complex to real
disabled), or decimate by 10 (complex to real enabled).
0100
FB2 + HB3 + HB2 + HB1 filter selection: decimate by 40 (complex
to real disabled), or decimate by 20 (complex to real enabled).
0111
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
0000 Use Register 0x0314, Bits[3:0].
0001 GPIO_B0, GPIO_A0.
0010 GPIO_B1, GPIO_A1.
0011 GPIO_A1, GPIO_A0.
0100 GPIO_B1, GPIO_B0.
0101 GPIO_B1, GPIO_A1, GPIO_B0, GPIO_A0.
0110 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
0000 Select NCO Channel 0.
0001 Select NCO Channel 1.
0010 Select NCO Channel 2.
0011 Select NCO Channel 3.
0100 Select NCO Channel 4.
0101 Select NCO Channel 5.
0110 Select NCO Channel 6.
0111 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.
AD9689 Data Sheet
Rev. A | Page 108 of 134
Addr. Name Bit(s) Bit Name Setting 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 POW for the NCO. 0x0 R/W
0x031E DDC0 Phase
Offset 1
[7:0] DDC0 phase
offset[15:8]
Twos complement POW for the NCO. 0x0 R/W
0x031F DDC0 Phase
Offset 2
[7:0] DDC0 phase
offset[23:16]
Twos complement POW for the NCO. 0x0 R/W
0x0320 DDC0 Phase
Offset 3
[7:0] DDC0 phase
offset[31:24]
Twos complement POW for the NCO. 0x0 R/W
0x0321 DDC0 Phase
Offset 4
[7:0] DDC0 phase
offset[39:32]
Twos complement POW for the NCO. 0x0 R/W
0x0322 DDC0 Phase
Offset 5
[7:0] DDC0 phase
offset[47:40]
Twos complement POW 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 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 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 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] DDC1 IF mode 0x0 R/W
00 Variable IF mode.
01 0 Hz IF mode.
10 fS Hz IF mode.
11 Test mode.
Data Sheet AD9689
Rev. A | Page 109 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
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 f
S
mixing
to convert to real.
[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
0000 TB2 + HB4 + HB3 + HB2 + HB1 filter selection: decimate by 48
(complex to real disabled), or decimate by 24 (complex to real
enabled).
0010 FB2 + HB1 filter selection: decimate by 10 (complex to real
disabled), or decimate by 5 (complex to real enabled).
0011 FB2 + HB2 + HB1 filter selection: decimate by 20 (complex to real
disabled), or decimate by 10 (complex to real enabled).
0100 FB2 + HB3 + HB2 + HB1 filter selection: decimate by 40 (complex
to real disabled), or decimate by 20 (complex to real enabled).
0111 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
0000
Use Register 0x0334, Bits[3:0].
0001
PIO_B0, GPIO_A0.
0010 GPIO_B1, GPIO_A1.
0011 GPIO_A1, GPIO_A0.
0100 GPIO_B1, GPIO_B0.
0101 GPIO_B1, GPIO_A1, GPIO_B0, GPIO_A0.
0110 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.
AD9689 Data Sheet
Rev. A | Page 110 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
[3:0] DDC1 NCO register
map channel select
NCO channel select register map control. 0x0 R/W
0000 Select NCO Channel 0.
0001
Select NCO Channel 1.
0010 Select NCO Channel 2.
0011 Select NCO Channel 3.
0100 Select NCO Channel 4.
0101 Select NCO Channel 5.
0110 Select NCO Channel 6.
0111 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 whose phase and offset are 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 POW for the NCO.
0x0
R/W
0x033E DDC1 Phase
Offset 1
[7:0] DDC1 phase
offset[15:8]
Twos complement POW for the NCO. 0x0 R/W
0x033F DDC1 Phase
Offset 2
[7:0] DDC1 phase
offset[23:16]
Twos complement POW for the NCO. 0x0 R/W
0x0340
DDC1 Phase
Offset 3
[7:0]
DDC1 phase
offset[31:24]
Twos complement POW for the NCO. 0x0 R/W
0x0341 DDC1 Phase
Offset 4
[7:0] DDC1 phase
offset[39:32]
Twos complement POW for the NCO. 0x0 R/W
0x0342 DDC1 Phase
Offset 5
[7:0] DDC1 phase
offset[47:40]
Twos complement POW 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 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 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.
Data Sheet AD9689
Rev. A | Page 111 of 134
Addr. Name Bit(s) Bit Name Setting 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 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] DDC2 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
000 TB2 + HB4 + HB3 + HB2 + HB1 filter selection: decimate by 48
(complex to real disabled), or decimate by 24 (complex to real
enabled).
0010 FB2 + HB1 filter selection: decimate by 10 (complex to real
disabled), or decimate by 5 (complex to real enabled).
011
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.
AD9689 Data Sheet
Rev. A | Page 112 of 134
Addr. Name Bit(s) Bit Name Setting 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
0000 Use Register 0x0354, Bits[3:0].
0001 GPIO_B0, GPIO_A0.
0010 GPIO_B1, GPIO_A1.
0011 GPIO_A1, GPIO_A0.
0100 GPIO_B1, GPIO_B0.
0101 GPIO_B1, GPIO_A1, GPIO_B0, GPIO_A0.
0110 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] DDC2 NCO register
map channel select
NCO channel select register map control. 0x0 R/W
0000 Select NCO Channel 0.
0001 Select NCO Channel 1.
0010 Select NCO Channel 2.
0011 Select NCO Channel 3.
0100 Select NCO Channel 4.
0101 Select NCO Channel 5.
0110 Select NCO Channel 6.
0111 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 are 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 POW for the NCO. 0x0 R/W
0x035E DDC2 Phase
Offset 1
[7:0] DDC2 phase
offset[15:8]
Twos complement POW for the NCO. 0x0 R/W
0x035F DDC2 Phase
Offset 2
[7:0] DDC2 phase
offset[23:16]
Twos complement POW for the NCO. 0x0 R/W
0x0360 DDC2 Phase
Offset 3
[7:0] DDC2 phase
offset[31:24]
Twos complement POW for the NCO. 0x0 R/W
0x0361 DDC2 Phase
Offset 4
[7:0] DDC2 phase
offset[39:32]
Twos complement POW for the NCO. 0x0 R/W
Data Sheet AD9689
Rev. A | Page 113 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
0x0362 DDC2 Phase
Offset 5
[7:0] DDC2 phase
offset[47:40]
Twos complement POW 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 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 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 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 f
S
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].
0x0371 DDC3 input
select
[7:4] DDC3 decimation rate
select
Only valid when Register 0x0310, Bits[2:0] = 3'b111. 0x0 R/W
000 TB2 + HB4 + HB3 + HB2 + HB1 filter selection: decimate by 48
(complex to real disabled), or decimate by 24 (complex to real
enabled).
010 FB2 + HB1 filter selection: decimate by 10 (complex to real
disabled), or decimate by 5 (complex to real enabled).
011 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
AD9689 Data Sheet
Rev. A | Page 114 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
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
0000
Use Register 0x0374, Bits[3:0].
0001 GPIO_B0, GPIO_A0.
0010 GPIO_B1, GPIO_A1.
0011 GPIO_A1, GPIO_A0.
0100 GPIO_B1, GPIO_B0.
0101 GPIO_B1, GPIO_A1, GPIO_B0, GPIO_A0.
0110 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
0000
Select NCO Channel 0.
0001
Select NCO Channel 1.
0010
Select NCO Channel 2.
0011 Select NCO Channel 3.
0100 Select NCO Channel 4.
0101 Select NCO Channel 5.
0110 Select NCO Channel 6.
0111 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.
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 POW for the NCO. 0x0 R/W
Data Sheet AD9689
Rev. A | Page 115 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
0x037E DDC3 Phase
Offset 1
[7:0] DDC3 phase
offset[15:8]
Twos complement POW for the NCO. 0x0 R/W
0x037F DDC3 Phase
Offset 2
[7:0] DDC3 phase
offset[23:16]
Twos complement POW for the NCO. 0x0 R/W
0x0380 DDC3 Phase
Offset 3
[7:0] DDC3 phase
offset[31:24]
Twos complement POW for the NCO. 0x0 R/W
0x0381 DDC3 Phase
Offset 4
[7:0] DDC3 phase
offset[39:32]
Twos complement POW for the NCO. 0x0 R/W
0x0382 DDC3 Phase
Offset 5
[7:0] DDC3 phase
offset[47:40]
Twos complement POW 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 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 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
Frac A0
[7:0] DDC0 Phase
Increment
Frac A[7:0]
Numerator correction term for Phase Accumulator MAW 0x0 R/W
0x0391 DDC0 Phase
Increment
Frac A1
[7:0] DDC0 Phase
Increment
Frac A[15:8]
Numerator correction term for MAW. 0x0 R/W
0x0392 DDC0 Phase
Increment
Frac A2
[7:0] DDC0 Phase
Increment
Frac A[23:16]
Numerator correction term for MAW. 0x0 R/W
0x0393
DDC0 Phase
Increment
Frac A3
[7:0]
DDC0 Phase
Increment
Frac A[31:24]
Numerator correction term for MAW. 0x0 R/W
0x0394 DDC0 Phase
Increment
Frac A4
[7:0] DDC0 Phase
Increment
Frac A[39:32]
Numerator correction term for MAW. 0x0 R/W
0x0395 DDC0 Phase
Increment
Frac A5
[7:0] DDC0 Phase
Increment
Frac A[47:40]
Numerator correction term for MAW. 0x0 R/W
0x0398 DDC0 Phase
Increment
Frac B0
[7:0] DDC0 Phase
Increment
Frac B[7:0]
Denominator correction term for Phase Accumulator MBW 0x0 R/W
0x0399 DDC0 Phase
Increment
Frac B1
[7:0] DDC0 Phase
Increment
Frac B[15:8]
Denominator correction term for MBW. 0x0 R/W
0x039A
DDC0 Phase
Increment
Frac B2
[7:0]
DDC0 Phase
Increment
Frac B[23:16]
Denominator correction term for MBW. 0x0 R/W
0x039B DDC0 Phase
Increment
Frac B3
[7:0] DDC0 Phase
Increment
Frac B[31:24]
Denominator correction term for MBW. 0x0 R/W
0x039C DDC0 Phase
Increment
Frac B4
[7:0] DDC0 Phase
Increment
Frac B[39:32]
Denominator correction term for MBW. 0x0 R/W
0x039D DDC0 Phase
Increment
Frac B5
[7:0] DDC0 Phase
Increment
Frac B[47:40]
Denominator correction term for MBW. 0x0 R/W
0x03A0 DDC1 Phase
Increment
Frac A0
[7:0] DDC1 Phase
Increment
Frac A[7:0]
Numerator correction term for MAW. 0x0 R/W
0x03A1 DDC1 Phase
Increment
Frac A1
[7:0] DDC1 Phase
Increment
Frac A[15:8]
Numerator correction term for MAW. 0x0 R/W
AD9689 Data Sheet
Rev. A | Page 116 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
0x03A2 DDC1 Phase
Increment
Frac A2
[7:0] DDC1 Phase
Increment
Frac A[23:16]
Numerator correction term for MAW. 0x0 R/W
0x03A3 DDC1 Phase
Increment
Frac A3
[7:0] DDC1 Phase
Increment
Frac A[31:24]
Numerator correction term for MAW. 0x0 R/W
0x03A4 DDC1 Phase
Increment
Frac A4
[7:0] DDC1 Phase
Increment
Frac A[39:32]
Numerator correction term for MAW. 0x0 R/W
0x03A5 DDC1 Phase
Increment
Frac A5
[7:0] DDC1 Phase
Increment
Frac A[47:40]
Numerator correction term for MAW. 0x0 R/W
0x03A8 DDC1 Phase
Increment
Frac B0
[7:0] DDC1 Phase
Increment
Frac B[7:0]
Denominator correction term for MBW. 0x0 R/W
0x03A9 DDC1 Phase
Increment
Frac B1
[7:0] DDC1 Phase
Increment
Frac B[15:8]
Denominator correction term for MBW. 0x0 R/W
0x03AA
DDC1 Phase
Increment
Frac B2
[7:0]
DDC1 Phase
Increment
Frac B[23:16]
Denominator correction term for MBW.
0x0
R/W
0x03AB DDC1 Phase
Increment
Frac B3
[7:0] DDC1 Phase
Increment
Frac B[31:24]
Denominator correction term for MBW. 0x0 R/W
0x03AC DDC1 Phase
Increment
Frac B4
[7:0] DDC1 Phase
Increment
Frac B[39:32]
Denominator correction term for MBW. 0x0 R/W
0x03AD DDC1 Phase
Increment
Frac B5
[7:0] DDC1 Phase
Increment
Frac B[47:40]
Denominator correction term for MBW. 0x0 R/W
0x03B0 DDC2 Phase
Increment
Frac A0
[7:0] DDC2 Phase
Increment
Frac A[7:0]
Numerator correction term for MAW. 0x0 R/W
0x03B1
DDC2 Phase
Increment
Frac A1
[7:0]
DDC2 Phase
Increment
Frac A[15:8]
Numerator correction term for MAW.
0x0
R/W
0x03B2 DDC2 Phase
Increment
Frac A2
[7:0] DDC2 Phase
Increment
Frac A[23:16]
Numerator correction term for MAW. 0x0 R/W
0x03B3 DDC2 Phase
Increment
Frac A3
[7:0] DDC2 Phase
Increment
Frac A[31:24]
Numerator correction term for MAW. 0x0 R/W
0x03B4 DDC2 Phase
Increment
Frac A4
[7:0] DDC2 Phase
Increment
Frac A[39:32]
Numerator correction term for MAW. 0x0 R/W
0x03B5 DDC2 Phase
Increment
Frac A5
[7:0] DDC2 Phase
Increment
Frac A[47:40]
Numerator correction term for MAW. 0x0 R/W
0x03B8 DDC2 Phase
Increment
Frac B0
[7:0] DDC2 Phase
Increment
Frac B[7:0]
Denominator correction term for MBW. 0x0 R/W
0x03B9 DDC2 Phase
Increment
Frac B1
[7:0] DDC2 Phase
Increment
Frac B[15:8]
Denominator correction term for MBW. 0x0 R/W
0x03BA DDC2 Phase
Increment
Frac B2
[7:0] DDC2 Phase
Increment
Frac B[23:16]
Denominator correction term for MBW. 0x0 R/W
0x03BB
DDC2 Phase
Increment
Frac B3
[7:0]
DDC2 Phase
Increment
Frac B[31:24]
Denominator correction term for MBW. 0x0 R/W
0x03BC DDC2 Phase
Increment
Frac B4
[7:0] DDC2 Phase
Increment
Frac B[39:32]
Denominator correction term for MBW. 0x0 R/W
0x03BD DDC2 Phase
Increment
Frac B5
[7:0] DDC2 Phase
Increment
Frac B[47:40]
Denominator correction term for MBW. 0x0 R/W
Data Sheet AD9689
Rev. A | Page 117 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
0x03C0 DDC3 Phase
Increment
Frac A0
[7:0] DDC3 Phase
Increment
Frac A[7:0]
Numerator correction term for MAW. 0x0 R/W
0x03C1 DDC3 Phase
Increment
Frac A1
[7:0] DDC3 Phase
Increment
Frac A[15:8]
Numerator correction term for MAW. 0x0 R/W
0x03C2 DDC3 Phase
Increment
Frac A2
[7:0] DDC3 Phase
Increment
Frac A[23:16]
Numerator correction term for MAW. 0x0 R/W
0x03C3 DDC3 Phase
Increment
Frac A3
[7:0] DDC3 Phase
Increment
Frac A[31:24]
Numerator correction term for MAW. 0x0 R/W
0x03C4 DDC3 Phase
Increment
Frac A4
[7:0] DDC3 Phase
Increment
Frac A[39:32]
Numerator correction term for MAW. 0x0 R/W
0x03C5 DDC3 Phase
Increment
Frac A5
[7:0] DDC3 Phase
Increment
Frac A[47:40]
Numerator correction term for MAW. 0x0 R/W
0x03C8
DDC3 Phase
Increment
Frac B0
[7:0]
DDC3 Phase
Increment
Frac B[7:0]
Denominator correction term for MBW.
0x0
R/W
0x03C9 DDC3 Phase
Increment
Frac B1
[7:0] DDC3 Phase
Increment
Frac B[15:8]
Denominator correction term for MBW. 0x0 R/W
0x03CA DDC3 Phase
Increment
Frac B2
[7:0] DDC3 Phase
Increment
Frac B[23:16]
Denominator correction term for MBW. 0x0 R/W
0x03CB DDC3 Phase
Increment
Frac B3
[7:0] DDC3 Phase
Increment
Frac B[31:24]
Denominator correction term for MBW. 0x0 R/W
0x03CC DDC3 Phase
Increment
Frac B4
[7:0] DDC3 Phase
Increment
Frac B[39:32]
Denominator correction term for MBW. 0x0 R/W
0x03CD
DDC3 Phase
Increment
Frac B5
[7:0]
DDC3 Phase
Increment
Frac B[47:40]
Denominator correction term for MBW.
0x0
R/W
Digital Outputs and Test Modes
Table 51.
Addr. Name Bit(s) Bit Name Setting Description Reset Access
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 Patten 1 MSB (0x0552) and User
Pattern 1 LSB (0x0551) registers. User Pattern 2 is found in the User
Pattern 2 MSB (0x0554) and User Pattern 2 LSB (0x0553) registers, 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 the following
user patterns: 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 the following user
patterns: 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.
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.
AD9689 Data Sheet
Rev. A | Page 118 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
[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 byte. 0x0 R/W
0x0556 User Pattern 3
MSB
[7:0] User Pattern 3[15:8] User Test Pattern 3 least significant byte. 0x0 R/W
0x0557 User Pattern 4
LSB
[7:0] User Pattern 4[7:0] User Test Pattern 4 least significant byte. 0x0 R/W
0x0558
User Pattern 4
MSB
[7:0]
User Pattern 4[15:8]
User Test Pattern 4 least significant byte.
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.
Data Sheet AD9689
Rev. A | Page 119 of 134
Addr. Name Bit(s) Bit Name Setting 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 has occurred.
1
Overrange has 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 16 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 fS × 4 mode enabled. L = 8; M = 2; F = 2; S = 4; N' = 16; N = 16;
CS = 0; CF = 0; HD = 0.
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 in 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).
AD9689 Data Sheet
Rev. A | Page 120 of 134
Addr. Name Bit(s) Bit Name Setting 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~ pin.
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 invert 0x0 R/W
0 Normal.
1 Invert a, b, c, d, e, f, g, h, i, 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
0000 Normal operation (test mode disabled).
0001 Alternating checkerboard.
0010 1/0 word toggle.
0011 31-bit PN sequence: x31 + x28 + 1.
0100 23-bit PN sequence: x23 + x18 + 1.
0101 15-bit PN sequence: x15 + x14 + 1.
0110 9-bit PN sequence: x9 + x5 + 1.
0111 7-bit PN sequence: x7 + x6 + 1.
1000 Ramp output.
1110 Continuous/repeat user test.
1111 Single user test.
Data Sheet AD9689
Rev. A | Page 121 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
0x0574 JESD204B Link
Control 4
[7:4] ILAS delay 0x0 R/W
0000
Transmit ILAS on first LMFC after SYNCINB± is deasserted.
0001 Transmit ILAS on second LMFC after SYNCINB± is deasserted.
0010 Transmit ILAS on third LMFC after SYNCINB± is deasserted.
0011
Transmit ILAS on fourth LMFC after SYNCINB± is deasserted.
0100 Transmit ILAS on fifth LMFC after SYNCINB± is deasserted.
0101
Transmit ILAS on sixth LMFC after SYNCINB± is deasserted.
0110 Transmit ILAS on seventh LMFC after SYNCINB± is deasserted.
0111
Transmit ILAS on eighth LMFC after SYNCINB± is deasserted.
1000 Transmit ILAS on ninth LMFC after SYNCINB± is deasserted.
1001
Transmit ILAS on tenth LMFC after SYNCINB± is deasserted.
1010
Transmit ILAS on eleventh LMFC after SYNCINB± is deasserted.
1011
Transmit ILAS on twelfth LMFC after SYNCINB± is deasserted.
1100 Transmit ILAS on thirteenth LMFC after SYNCINB± is deasserted.
1101 Transmit ILAS on fourteenth LMFC after SYNCINB± is deasserted.
1110
Transmit ILAS on fifteenth LMFC after SYNCINB± is deasserted.
1111 Transmit ILAS on sixteenth LMFC after SYNCINB± is 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
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 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 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 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 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 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 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 LID number for Lane 7.
0x7
R/W
AD9689 Data Sheet
Rev. A | Page 122 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
0x058B JESD204B
scrambling
and number
of 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 = 0x058C[7:0] + 1)
0x0 R/W
0000 F = 1.
0001 F = 2.
0010 F = 3.
0011 F = 4.
0101 F = 6.
0111 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 = 0x058C[4:0] + 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 per device
(M = JESD204B M configuration).
0x1 R/W
000 Link connected to one virtual converter (M = 1).
001
Link connected to two virtual converters (M = 2).
011 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
000 No control bits (CS = 0).
001 1 control bit (CS = 1), Control Bit 2 only.
010 2 control bits (CS = 2), Control Bit 2 and Control Bit 1 only.
011 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.
Data Sheet AD9689
Rev. A | Page 123 of 134
Addr. Name Bit(s) Bit Name Setting 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 = 0x0591[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.
AD9689 Data Sheet
Rev. A | Page 124 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
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.
0x05B2
JESD204B
Lane Assign 1
7
Reserved
Reserved.
0x0
R
[6:4] SERDOUT1± lane
assignment
Physical Lane 1 assignment. 0x1 R/W
000 Logical Lane 0.
001 Logical Lane 1 (default).
010 Logical Lane 2.
011 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
000 Logical Lane 0 (default).
001 Logical Lane 1.
010 Logical Lane 2.
011 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
000 Logical Lane 0.
001 Logical Lane 1.
010 Logical Lane 2.
011 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
000 Logical Lane 0.
001 Logical Lane 1.
010 Logical Lane 2 (default).
011 Logical Lane 3.
100 Logical Lane 4.
101 Logical Lane 5.
110 Logical Lane 6.
111 Logical Lane 7.
Data Sheet AD9689
Rev. A | Page 125 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
0x05B5 JESD204B
Lane Assign 3
7 Reserved Reserved. 0x0 R
[6:4] SERDOUT5± lane
assignment
Physical Lane 5 assignment. 0x5 R/W
000 Logical Lane 0.
001 Logical Lane 1.
010 Logical Lane 2.
011 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
[2:0] SERDOUT4± lane
assignment
Physical Lane 4 assignment. 0x4 R/W
000 Logical Lane 0.
001 Logical Lane 1.
010 Logical Lane 2.
011 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
000 Logical Lane 0.
001 Logical Lane 1.
010 Logical Lane 2.
011 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
000 Logical Lane 0.
001 Logical Lane 1.
010 Logical Lane 2.
011 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.
AD9689 Data Sheet
Rev. A | Page 126 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
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.
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
Data Sheet AD9689
Rev. A | Page 127 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
[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.
0x05C4 SERDOUT0
de-emphasis
select
7 Posttap enable Posttap enable. 0x0 R/W
0 Disable.
1 Enable.
[6:4]
Set posttap level for
SERDOUT0±
Set posttap 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
de-emphasis
select
7 Posttap enable Posttap enable. 0x0 R/W
0 Disable.
1 Enable.
[6:4] Set posttap level for
SERDOUT1±
Set posttap 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
de-emphasis
select
7 Posttap enable Posttap enable. 0x0 R/W
0 Disable.
1 Enable.
[6:4] Set posttap level for
SERDOUT2±
Set posttap 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
de-emphasis
select
7 Posttap enable Posttap enable. 0x0 R/W
0 Disable.
1 Enable.
[6:4] Set posttap level for
SERDOUT3±
Set posttap 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
AD9689 Data Sheet
Rev. A | Page 128 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
0x05C8 SERDOUT4
de-emphasis
select
7 Posttap enable Posttap enable. 0x0 R/W
0 Disable.
1
Enable.
[6:4] Set posttap level for
SERDOUT4±
Set posttap 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
0x05C9 SERDOUT5
preemphasis
select
7 Posttap enable Posttap enable. 0x0 R/W
0 Disable.
1 Enable.
[6:4] Set posttap level for
SERDOUT5±
Set posttap 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
preemphasis
select
7 Posttap enable Posttap enable. 0x0 R/W
0 Disable.
1 Enable.
[6:4] Set posttap level for
SERDOUT6±
Set posttap 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
preemphasis
select
7 Posttap enable Posttap enable. 0x0 R/W
0 Disable.
1
Enable.
[6:4] Set posttap level for
SERDOUT7±
Set posttap 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] JESD204B PLL
calibration reset
See Table 32. 0x00 R/W
0x00 JESD204B PLL normal operation.
0x04 Reset JESD204B PLL calibration.
0x1228 JESD204B PLL
startup
control
[7:0] JESD204B PLL
calibration startup
circuit reset
See Table 32. 0x0F R/W
0x0F JESD204B start-up circuit in normal operation.
0x4F Reset JESD204B startup circuit.
Data Sheet AD9689
Rev. A | Page 129 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
0x1262 JESD204B PLL
LOL bit
control
[7:0] JESD204B PLL loss of
lock bit clear
See Table 32. 0x00 R/W
0x00 Loss of lock bit normal operation.
0x80
Clear loss of lock bit.
Programmable Filter (PFILT) Control and Coefficients Registers
Table 52.
Addr. Name Bit(s) Bit Name Setting Description Reset Access
0x0DF8 Programmable
filter control
[7:3] Reserved Reserved. 0x0 R
[2:0] Programmable filter
mode
PFILT mode. The asterisk symbol (*) denotes convolution. 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
to
0x0E7F
Programmable
Filter X
Coefficient x
[7:0] Programmable Filter X
Coefficient 0 to 127
Refer to the I coefficient table (Table 14) and the Q coefficient table
(Table 15) in the Programmable FIR Filters section for details.
Coefficients are only applied after the chip transfer bit
(Register 0x000F, Bit 0) is set.
0x0 R/W
0x0F00
to
0x0F7F
Programmable
Filter Y Coefficient
x
[7:0]
Programmable Filter Y
Coefficient 0 to 127
Refer to the I coefficient table (Table 14) and the Q coefficient table
(Table 15) in the Programmable FIR Filters section for details.
Coefficients are only applied after the chip transfer bit
(Register 0x000F, Bit 0) is set.
0x0
R/W
AD9689 Data Sheet
Rev. A | Page 130 of 134
VREF/Analog Input Control Registers
Table 53.
Addr. Name Bit(s) Bit Name Setting Description Reset Access
0x0701
DC offset
calibration control
(local)
[7:0]
DC offset calibration
control
0x06 R/W
0x06 Disable.
0x86 Enable.
0x073B DC Offset
Calibration
Control 2 (local)
[7:0] DC offset calibration
accumulator reset
Synchronously reset dc offset calibration accumulator. 0xB7 R/W
0xB7 Accumulator held in reset (use when 0x0701 = 0x06).
0x37 Accumulator reset released (use when 0x0701 = 0x86).
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 V
CM
buffer[5:0]
See the Input Common Mode section.
0x0
R/W
0x18E6
Temperature diode
export
[7:0] Temperature diode
location select
0x0 R/W
0x00 Central diode output. VREF pin = high-Z.
0x01 Central diode output. VREF pin = 1× diode voltage output.
0x02 Central diode output. VREF pin = 20× diode voltage output.
0x03 Central diode output. VREF pin = GND.
0x40 Channel A diode output. VREF pin = high-Z.
0x41 Channel A diode output. VREF pin = 1× diode voltage output.
0x42 Channel A diode output. VREF pin = 20× diode voltage output.
0x43 Channel A diode output. VREF pin = GND.
0x50 Channel B diode output VREF pin = high-Z.
0x51 Channel B diode output VREF pin = 1× diode voltage output.
0x52
Channel B diode output VREF pin = 20× diode voltage output.
0x53
Channel B diode output 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]
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.
Data Sheet AD9689
Rev. A | Page 131 of 134
Addr. Name Bit(s) Bit Name Setting Description Reset Access
0x1A48 High frequency
setting (local)
[7:0] High frequency setting 0x14 R/W
0x14 First Nyquist operation.
0x54 Second or higher Nyquist operation.
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.
0x0F R/W
00 1111 Buffer current set to 300 μA
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.
10 1101 Buffer current set to 900 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.
0x0F R/W
00 1111 Buffer current set to 300 μA
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.
10 1101 Buffer current set to 900 μA.
11 0010 Buffer current set to 1000 μA.
AD9689 Data Sheet
Rev. A | Page 132 of 134
APPLICATIONS INFORMATION
POWER SUPPLY RECOMMENDATIONS
The power supplies required to power the AD9689 are
shown in Table 54. A power-on sequence is not required to
operate the AD9689. The power supply domains can be
powered up in any order.
Table 54. Typical Power Supplies for the AD9689
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 LT3045). Figure 157 shows the recommended power supply
scheme for the AD9689.
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
REF E RENCED TO AGND
OPTIONAL
ADP1763
ADP1763
LT3045
LT3045
LT3045
15550-072
Figure 157. High Efficiency, Low Noise Power Solution for the AD9689
It is not necessary to split all of these power domains in all cases.
The recommended solution shown in Figure 157 provides the
lowest noise, highest efficiency power delivery system for the
AD9689. 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 158 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
AD9689 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 inserted 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 FRO M F MC O R
6.0 V FROM WALL
SUPPLY
AVDD3
2.5V
3.0V
LDO
SWITCHER
OPTIONAL PATH
FERRITE BE AD
1.3V
DIGITAL
2.4V
SW3
SW4
SW1
SW2
ADP1763
LT3045
LT3045
SPIVDD
1.9V
NOTES
1. AL L VO LT AGES RE FERENCE D TO AGND.
15550-327
Figure 158. Simplified Power Solution for the AD9689
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 AD9689
Rev. A | Page 133 of 134
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 159 shows the overall layout scheme used for the
AD9689 evaluation boards.
AVDD1_SR (PIN E7) AND AGND (PIN E6 AND PIN E8)
Use AVDD1_SR (Pin E7) and AGND (Pin E6 and Pin E8) to
provide a separate power supply node to the SYSREF± circuits
of the AD9689. If running in Subclass 1, the AD9689 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
15550-328
Figure 159. Recommended PCB Layout for the AD9689
AD9689 Data Sheet
Rev. A | Page 134 of 134
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
01 91141 31 21 13 246 578
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 160. 196-Ball Ball Grid Array, Thermally Enhanced [BGA_ED]
12 mm × 12 mm (BP-196-4)
Dimensions shown in millimeters
ORDERING GUIDE
Model 1 Temperature Range Package Description Package Option
AD9689BBPZ-2000 −40°C to +85°C 196-Ball Ball Grid Array, Thermally Enhanced [BGA_ED] BP-196-4
AD9689BBPZRL-2000 −40°C to +85°C 196-Ball Ball Grid Array, Thermally Enhanced [BGA_ED] BP-196-4
AD9689BBPZ-2600 −40°C to +85°C 196-Ball Ball Grid Array, Thermally Enhanced [BGA_ED] BP-196-4
AD9689BBPZRL-2600 −40°C to +85°C 196-Ball Ball Grid Array, Thermally Enhanced [BGA_ED] BP-196-4
AD9689-2000EBZ Evaluation Board
AD9689-2600EBZ 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.
D15550-0-10/17(A)
