Mixed-Signal Front End for Broadband Applications AD9878 FEATURES Low cost 3.3 V CMOS MxFETM for broadband applications DOCSIS, EURO-DOCSIS, DVB, DAVIC compliant 232 MHz quadrature digital upconverter 12-bit direct IF DAC (TxDAC+TM) Up to 65 MHz carrier frequency DDS Programmable sampling clock rates Analog Tx output level adjust Dual 12-bit, 29 MSPS direct IF ADCs with video clamp input 10-bit, 29 MSPS sampling ADC 8-bit sigma-delta auxiliary DAC Direct interface to AD8321/AD8323 or AD8322/AD8327 PGA cable driver FUNCTIONAL BLOCK DIAGRAM I Tx Tx D A TA Q 12 DAC Tx DDS - SPO R T 4 - _ OU T 3 C ON TR O L R EGISTER S C A IN T MC L K PLL IF1 0 [4 :0 ] MU X 10 12 OSC IN Rx10 ADC ADC Rx12B MU X IF1 2 [1 1 :0 ] FL A G[2 :1 ] VID EO - C LA MP L EVEL MU X 12 APPLICATIONS SIN C - 1 16 MU X Rx12A ADC Cable set-top boxes Cable and wireless modems 03277- 0- 001 Figure 1. Functional Block Diagram GENERAL DESCRIPTION The AD9878 is a single-supply cable modem/set-top box mixed-signal front end. The device contains a transmit path interpolation filter, a complete quadrature digital upconverter, and transmit DAC. The receive path contains dual 12-bit ADCs and a 10-bit ADC. All internally required clocks and an output system clock are generated by the PLL from a single crystal oscillator or clock input. The transmit path interpolation filter provides an upsampling factor of 16x with an output signal bandwidth up to 5.8 MHz. Carrier frequencies up to 65 MHz with 26 bits of frequency tuning resolution can be generated by the direct digital synthesizer (DDS). The transmit DAC resolution is 12 bits and can run at sampling rates as high as 232 MSPS. Analog output scaling from 0 dB to 7.5 dB in 0.5 dB steps is available to preserve SNR when reduced output levels are required. The 12-bit ADCs provide excellent undersampling performance, allowing this device to deliver better than 10 ENOBs with IF inputs up to 70 MHz. The 12-bit IF ADCs can sample at rates up to 29 MHz, allowing them to process wideband signals. The AD9878 includes a programmable sigma-delta DAC, which can be used to control an external component such as a variable gain amplifier (VGA) or a voltage controlled tuner. The AD9878 also integrates a CA port that enables a host processor to interface with the AD8321/AD8323 or AD8322/AD8327/AD8328 programmable gain amplifier (PGA) cable drivers via the MxFE serial port (SPORT). The AD9878 is available in a 100-lead LQFP package. The AD9878 is specified over the extended industrial (-40C to +85C) temperature range. Rev. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective companies. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.326.8703 (c) 2003 Analog Devices, Inc. All rights reserved. AD9878 TABLE OF CONTENTS SPECIFICATIONS ........................................................................... 3 INTERPOLATION FILTER ..................................................... 18 ABSOLUTE MAXIMUM RATINGS............................................. 6 DIGITAL UPCONVERTER ..................................................... 19 DEFINITIONS OF SPECIFICATIONS......................................... 7 CLOCK AND OSCILLATOR CIRCUITRY........................... 21 TYPICAL PERFORMANCE CHARACTERISTICS ................... 8 PROGRAMMABLE CLOCK OUTPUT REFCLK................ 22 REGISTER BIT DEFINITIONS ................................................... 11 RESET AND TRANSMIT POWER-DOWN ......................... 23 SERIAL INTERFACE FOR REGISTER CONTROL ................. 15 RECEIVE PATH (Rx) ................................................................ 24 GENERAL OPERATION OF THE SERIAL INTERFACE... 15 PCB DESIGN CONSIDERATIONS ........................................ 25 INSTRUCTION BYTE .............................................................. 15 PIN CONFIGURATION AND PIN FUNCTION DESCRIPTIOINS ........................................................................... 27 SERIAL INTERFACE PORT PIN DESCRIPTION ............... 15 MSB/LSB TRANSFERS ............................................................. 16 NOTES ON SERIAL PORT OPERATION ............................. 16 OUTLINE DIMENSIONS ............................................................ 34 ORDERING GUIDE.................................................................. 34 THEORY OF OPERATION.......................................................... 17 TRANSMIT PATH..................................................................... 18 REVISION HISTORY Revision 0: Initial Version Rev. 0 | Page 2 of 36 AD9878 SPECIFICATIONS Table 1. ELECTRICAL CHARACTERISTICS (VAS = 3.3 V 5%, VDS = 3.3 V 10%, fOSCIN = 27 MHz, fSYSCLK = 216 MHz, fMCLK = 54 MHz (M = 8), ADC Clock Derived from OSCIN, RSET = 4.02 k, Max. Fine Gain, 75 DAC Load.) PARAMETER OSCIN and XTAL CHARACTERISTICS Frequency Range Duty Cycle Input Impedance MCLK Cycle to Cycle Jitter (fMCLK derived from PLL) Tx DAC CHARACTERISTICS Maximum Sample Rate Resolution Full-Scale Output Current Gain Error (Using Internal Reference) Offset Error Reference Voltage (REFIO Level) Differential Nonlinearity (DNL) Integral Nonlinearity (INL) Output Capacitance Phase Noise @ 1 kHz Offset, 42 MHz Carrier Output Voltage Compliance Range Wideband SFDR 5 MHz Analog Out, IOUT = 10 mA 65 MHz Analog Out, IOUT = 10 mA Narrow-Band SFDR (1 MHz Window) 5 MHz Analog Out, IOUT = 10 mA 65 MHz Analog Out, IOUT = 10 mA Tx MODULATOR CHARACTERISTICS I/Q Offset Pass-Band Amplitude Ripple (f < fIQCLK/8) Pass-Band Amplitude Ripple (f < fIQCLK/4) Stop-Band Response (f > fIQCLK x 3/4) Tx GAIN CONTROL Gain Step Size Gain Step Error Settling Time, 1% (Full-Scale Step) 10-BIT ADC CHARACTERISTICS Resolution Maximum Conversion Rate Pipeline Delay Analog Input Input Voltage Range Differential Input Impedance Full Power Bandwidth Dynamic Performance (f = 5 MHz) Signal-to-Noise and Distortion (SINAD) Effective Number of Bits (ENOB) Total Harmonic Distortion (THD) Spurious-Free Dynamic Range (SFDR) Reference Voltage Error, REFT10-REFB10 (1.0 V) Temp Test Level Full 25C 25C 25C II II III III 3 35 Full N/A Full Full 25C 25C 25C 25C 25C 25C Full II N/A II II III III III III III III II 232 Full Full I I 62.4 50.3 68 53.5 dB dB Full Full I I 71 61 74 64 dB dB Full Full Full Full II II II II 50 55 25C 25C 25C III III III Min 4 -2.5 Typ 50 100||3 6 12 10 -1 1.0 1.23 2.5 8 5 -110 Max Unit 29 65 MHz % M||pF ps rms 20 +2.5 +1.5 -0.5 0.1 0.5 -63 N/A Full N/A N/A II N/A Full 25C 25C II III III Full Full Full Full Full I I I I I 65.7 Rev. 0 | Page 3 of 36 dB dB dB dB 0.5 <0.05 1.8 dB dB s 10 4.5 Bits MHz ADC cycles 2 4||2 90 Vppd k||pF MHz 59.7 9.6 -71.1 72.4 4 dB Bits dB dB mV 29 57.6 9.2 MHz Bits mA % FS % FS V LSB LSB pF dBc/Hz V -63.6 200 AD9878 PARAMETER Dynamic Performance (f = 50 MHz) Signal-to-Noise and Distortion (SINAD) Effective Number of Bits (ENOB) Total Harmonic Distortion (THD) Spurious-Free Dynamic Range (SFDR) 12-BIT ADC CHARACTERISTICS Resolution Maximum Conversion Rate Pipeline Delay Analog Input Input Voltage Range Differential Input Impedance Aperture Delay Aperture Uncertainty (Jitter) Full Power Bandwidth Input Referred Noise Reference Voltage Error, REFT12-REFB12 (1 V) Dynamic Performance (AIN = -0.5 dBFS, f = 5 MHz) Temp Test Level Full Full Full Full I I I I N/A Full N/A N/A II N/A Full 25C 25C 25C 25C 25C Full III III III III III III I Full Full Full Full Full I I I I I 61.0 9.8 64.2 Full Full Full Full Full II II II II II 60.4 9.74 62.4 Full Full Full Full Full 25C 25C II II II II II III III 59.4 9.5 61.6 Full Full Full Full II II II II 46.7 54.3 Min Typ 54.8 8.8 57.8 9.3 -63.3 63.7 56.9 Max -56.9 dB Bits dB dB 5.5 Bits MHz ADC cycles 2 4||2 2.0 1.2 85 75 16 Vppd k||pF ns ps rms MHz V mV 12 29 -200 Unit +200 ADC Sample Clock = OSCIN Signal-to-Noise and Distortion (SINAD) Effective Number of Bits (ENOBs) Signal-to-Noise Ratio (SNR) Total Harmonic Distortion (THD) Spurious-Free Dynamic Range (SFDR) 62.8 67 10.8 66 -72.7 74.6 -61.7 dB Bits dB dB dB ADC Sample Clock = PLL Signal-to-Noise and Distortion (SINAD) Effective Number of Bits (ENOBs) Signal-to-Noise Ratio (SNR) Total Harmonic Distortion (THD) Spurious-Free Dynamic Range (SFDR) Dynamic Performance (AIN = -0.5 dBFS, f = 50 MHz) 62.7 64.4 10.4 65.1 -72.7 74.6 -61.8 dB Bits dB dB dB ADC Sample Clock = OSCIN Signal-to-Noise and Distortion (SINAD) Effective Number of Bits (ENOB) Signal-to-Noise Ratio (SNR) Total Harmonic Distortion (THD) Spurious-Free Dynamic Range (SFDR) Differential Phase Differential Gain 62.5 62.9 10.1 63.7 -71.7 72 <0.1 <1 -61.5 dB Bits dB dB dB Degrees LSB VIDEO ADC PERFORMANCE (f = 5 MHz) ADC Sample Clock = OSCIN Signal-to-Noise and Distortion (SINAD) Signal-to-Noise Ratio (SNR) Total Harmonic Distortion (THD) Spurious-Free Dynamic Range (SFDR) 45.9 Rev. 0 | Page 4 of 36 53 63.2 -50.2 50 -45.9 dB Bits dB dB AD9878 PARAMETER CHANNEL-TO-CHANNEL ISOLATION Tx DAC-to-ADC Isolation (5 MHz Analog Output) Isolation between Tx and 10-Bit ADC Isolation between Tx and 12-Bit ADCs ADC-to-ADC Isolation (AIN = -0.5 dBFS, f = 5 MHz) Isolation between IF10 and IF12A/B Isolation between IF12A and IF12B TIMING CHARACTERISTICS (10 pF LOAD) Wake-Up Time Minimum RESET Pulsewidth Low (tRL) Digital Output Rise/Fall Time Tx/Rx Interface MCLK Frequency (fMCLK) TxSYNC/TxIQ Setup Time (tSU) TxSYNC/TxIQ Hold Time (tHD) MCLK Rising Edge to RxSYNC Valid Delay (tMD) OSCOUT Rising or Falling Edge to RxSYNC Valid Delay (tOD) OSCOUT Edge to MCLK Falling Edge (tEE) SERIAL CONTROL BUS Maximum SCLK Frequency (fSCLK) Minimum Clock Pulsewidth High (tPWH) Minimum Clock Pulsewidth Low (tPWL) Maximum Clock Rise/Fall Time Minimum Data/Chip-Select Setup Time (tDS) Minimum Data Hold Time (tDH) Maximum Data Valid Time (tDV) CMOS LOGIC INPUTS Logic "1" Voltage Logic "0" Voltage Logic "1" Current Logic "0" Current Input Capacitance CMOS LOGIC OUTPUTS (1 mA Load) Logic "1" Voltage Logic "0" Voltage POWER SUPPLY Supply Current, IS (Full Operation) Analog Supply Current IAS Digital Supply Current IDS Supply Current, IS Standby (PWRDN Pin Active) Full Power-Down (Register 02 = 0xFF) Power-Down Tx Path (Register 02 = 0x60) Power-Down IF12 Rx Paths (Register 02 = 0x1B) Power Supply Rejection (Differential Signal) Tx DAC 10-Bit ADC 12-Bit ADC Temp Test Level 25C 25C III III >60 >80 dB dB 25C 25C III III >85 >85 dB dB N/A N/A Full N/A N/A II 5 2.8 Full Full Full Full II II II II 3 3 0 1.0 MHz ns ns ns Full Full II II TOSC/4 - 2.0 -1.0 TOSC/4 + 3.0 +1.0 ns ns Full Full Full Full Full Full Full II II II II II II II 15 MHz ns ns s ns ns ns 25C 25C 25C 25C 25C II II II II III VDRVDD - 0.7 25C 25C II II VDRVDD - 0.6 25C 25C 25C II III III 25C 25C 25C 25C 25C 25C 25C Min Typ Max 200 4 66 30 30 1 25 0 30 0.4 12 12 3 Unit TMCLK cycles tMCLK cycles ns V V A A pF 0.4 V V 184 105 79 204 115 89 mA mA mA II III III III 46 46 124 131 53 52 mA mA mA mA III III III <0.25 <0.0001 <0.0004 Rev. 0 | Page 5 of 36 159 % FS % FS % FS AD9878 ABSOLUTE MAXIMUM RATINGS Table 2. Parameter Power Supply (VAVDD, VDVDD, VDRVDD) Digital Output Current Digital Inputs Analog Inputs Operating Temperature Maximum Junction Temperature Storage Temperature Lead Temperature (Soldering 10 sec) Rating 3.9 V 5 mA -0.3 V to VDRVDD + 0.3 V -0.3 V to VAVDD + 0.3 V -40C to +85C 150C -65C to +150C 300C Absolute maximum ratings are limiting values, to be applied individually, and beyond which the serviceability of the circuit may be impaired. Functional operability under any of these conditions is not necessarily implied. Exposure to absolute maximum rating conditions for extended periods of time may affect device reliability. EXPLANATION OF TEST LEVELS I. Devices are 100% production tested at 25C and guaranteed by design and characterization testing for industrial operating temperature range (-40C to +85C). II. Parameter is guaranteed by design and/or characterization testing. III. Parameter is a typical value only. N/A. Test level definition is not applicable. THERMAL CHARACTERISTICS Thermal Resistance: 100-Lead LQFP: JA = 40.5C/W Rev. 0 | Page 6 of 36 AD9878 DEFINITIONS OF SPECIFICATIONS Differential Nonlinearity Error (DNL, No Missing Codes) An ideal converter exhibits code transitions that are exactly 1 LSB apart. DNL is the deviation from this ideal value. Guaranteed no missing codes to 10-bit resolution indicates that all 1,024 codes, respectively, must be present over all operating ranges. Integral Nonlinearity Error (INL) Linearity error refers to the deviation of each individual code from a line drawn from negative full scale through positive full scale. The point used as negative full scale occurs 1/2 LSB before the first code transition. Positive full scale is defined as a level 11/2 LSB beyond the last code transition. The deviation is measured from the middle of each particular code to the true straight line. Phase Noise Single-sideband phase noise power is specified relative to the carrier (dBc/Hz) at a given frequency offset (1 kHz) from the carrier. Phase noise can be measured directly in single-tone transmit mode with a spectrum analyzer that supports noise marker measurements. It detects the relative power between the carrier and the offset (1 kHz) sideband noise and takes the resolution bandwidth (rbw) into account by subtracting 10 x log(rbw). It also adds a correction factor that compensates for the implementation of the resolution bandwidth, log display, and detector characteristic. Output Compliance Range The range of allowable voltage at the output of a current-output DAC. Operation beyond the maximum compliance limits may cause either output stage saturation or breakdown, resulting in nonlinear performance. Spurious-Free Dynamic Range (SFDR) The difference, in dB, between the rms amplitude of the DAC's output signal (or ADC's input signal) and the peak spurious signal over the specified bandwidth (Nyquist bandwidth, unless otherwise noted). Pipeline Delay (Latency) The number of clock cycles between conversion initiation and the associated output data being made available. Offset Error The first code transition should occur at an analog value 1/2 LSB above negative full scale. Offset error is defined as the deviation of the actual transition from that point. Gain Error The first code transition should occur at an analog value 1/2 LSB above negative full scale. The last transition should occur for an analog value 11/2 LSB below the nominal full scale. Gain error is the deviation of the actual difference between first and last code transitions and the ideal difference between first and last code transitions. Aperture Delay The aperture delay is a measure of the Sample-and-Hold Amplifier (SHA) performance that specifies the time delay between the rising edge of the sampling clock input to when the input signal is held for conversion. Aperture Uncertainty (Jitter) Aperture jitter is the variation in aperture delay for successive samples and is manifested as noise on the input to the ADC. Input Referred Noise The rms output noise is measured using histogram techniques. The ADC output codes' standard deviation is calculated in LSB, and converted to an equivalent voltage. This results in a noise figure that can be directly referred to the input of the MxFE. Signal-to-Noise and Distortion (S/N+D, SINAD) Ratio S/N+D is the ratio of the rms value of the measured input signal to the rms sum of all other spectral components below the Nyquist frequency, including harmonics but excluding dc. The value for S/N+D is expressed in decibels. Effective Number of Bits (ENOB) For a sine wave, SINAD can be expressed in terms of the number of bits. Using the following formula, it is possible to get a measure of performance expressed as N, the effective number of bits: N = (SINAD - 1.76)dB/6.02 Thus, the effective number of bits for a device for sine wave inputs at a given input frequency can be calculated directly from its measured SINAD. Signal-to-Noise Ratio (SNR) SNR is the ratio of the rms value of the measured input signal to the rms sum of all other spectral components below the Nyquist frequency, excluding harmonics and dc. The value for SNR is expressed in decibels. Total Harmonic Distortion (THD) THD is the ratio of the rms sum of the first six harmonic components to the rms value of the measured input signal, and is expressed as a percentage or in decibels. Power Supply Rejection Power supply rejection specifies the converter's maximum fullscale change when the supplies are varied from nominal to minimum and maximum specified voltages. Channel-to-Channel Isolation (Crosstalk) In an ideal multichannel system, the signal in one channel will not influence the signal level of another channel. The channelto-channel isolation specification is a measure of the change that occurs in a grounded channel as a full-scale signal is applied to another channel. Rev. 0 | Page 7 of 36 AD9878 0 0 -10 -10 -20 -20 -30 -30 MAGNITUDE - dB MAGNITUDE - dB TYPICAL PERFORMANCE CHARACTERISTICS -40 -50 -60 -70 -40 -50 -60 -70 -80 -80 -90 -90 -100 -100 55 0 2 4 6 8 10 12 14 FREQUENCY - MHz 16 18 20 57 59 61 63 65 67 69 FREQUENCY - MHz 71 Figure 5. Dual Sideband Spectral Plot, fC = 65 MHz, f = 1 MHz, RSET = 4 k (IOUT = 10 mA), RBW = 1 kHz 0 0 -10 -10 -20 -20 -30 -30 MAGNITUDE - dB MAGNITUDE - dB Figure 2. Dual Sideband Spectral Plot, fC = 5 MHz, f = 1 MHz, RSET =10 k (IOUT = 4 mA), RBW = 1 kHz -40 -50 -60 -70 -40 -50 -60 -70 -80 -80 -90 -90 0 2 4 6 8 10 12 14 FREQUENCY - MHz 16 18 -100 20 0 20 40 60 80 FREQUENCY - MHz 100 Figure 6. Single Sideband @ 65 MHz, RBW = 2 kHz, fC = 66 MHz, f = 1 MHz, RSET = 10 k (IOUT = 4 mA) 0 0 -10 -10 -20 -20 -30 -30 MAGNITUDE - dB MAGNITUDE - dB Figure 3. Dual Sideband Spectral Plot, fC = 5 MHz, f = 1 MHz, RSET = 4 k (IOUT = 10 mA), RBW=1 kHz -40 -50 -60 -70 -40 -50 -60 -70 -80 -80 -90 -90 -100 57 59 61 63 65 67 69 FREQUENCY - MHz 70 73 120 03277- 0- 026 03277- 0- 023 -100 55 75 03277- 0- 025 03277- 0- 022 -100 73 75 0 20 40 60 80 FREQUENCY - MHz 100 120 03277- 0- 027 03277- 0- 024 Figure 7. Single Sideband @ 65 MHz, RBW = 2 kHz, fC = 66 MHz, f = 1 MHz, RSET = 4 k (IOUT = 10 mA) Figure 4. Dual Sideband Spectral Plot, fC = 65 MHz, f = 1 MHz, RSET =10 k (IOUT = 4 mA), RBW = 1 kHz Rev. 0 | Page 8 of 36 AD9878 0 0 -10 -10 -20 -20 MAGNITUDE - dB MAGNITUDE - dB -30 -40 -50 -60 -70 0 20 40 60 80 FREQUENCY - MHz 100 -60 -90 120 0 -10 -10 -20 -20 -30 -30 MAGNITUDE - dB 0 -40 -50 -60 -60 -80 -80 40 60 80 FREQUENCY - MHz 100 -90 -2.5 120 -2.0 -1.5 -1.0 03277- 0- 029 Figure 9. Single Sideband @ 42 MHz, RBW = 2 kHz, fC = 43 MHz, f = 1 MHz, RSET = 4 k (IOUT = 10 mA) -0.5 0 0.5 1.0 FREQUENCY - MHz 1.5 2.0 2.5 03277- 0- 032 Figure 12. Single Sideband @ 65 MHz, RBW = 500 Hz, fC = 66 MHz, f = 1 MHz, RSET = 10 k (IOUT = 4 mA) 0 0 -10 -10 -20 -20 MAGNITUDE - dB -30 -40 -50 -60 -70 -30 -40 -50 -60 -70 -80 -80 -90 -100 03277- 0- 031 -50 -70 20 120 100 -40 -70 0 40 60 80 FREQUENCY - MHz Figure 11. Single Sideband @ 5 MHz, RBW = 2 kHz, fC = 6 MHz, f = 1 MHz, RSET = 4 k (IOUT = 10 mA) 0 -90 20 03277- 0- 028 Figure 8. Single Sideband @ 42 MHz, RBW = 2 kHz ,fC = 43 MHz, f = 1 MHz, RSET = 10 k (IOUT = 4 mA) MAGNITUDE - dB -50 -80 -90 MAGNITUDE - dB -40 -70 -80 -100 -30 0 20 40 60 80 FREQUENCY - MHz 100 -90 -2.5 120 03277- 0- 030 Figure 10. Single Sideband @ 5 MHz, RBW = 2 kHz, fC = 6 MHz, f = 1 MHz, RSET = 10 k (IOUT = 4 mA) -2.0 -1.5 -1.0 -0.5 0 0.5 1.0 FREQUENCY - MHz 1.5 2.0 2.5 03277- 0- 033 Figure 13. Single Sideband @ 65 MHz, RBW = 500 Hz, fC = 66 MHz, f = 1 MHz, RSET = 4 k (IOUT = 10 mA) Rev. 0 | Page 9 of 36 AD9878 0 0 -10 -10 -20 -20 MAGNITUDE - dB MAGNITUDE - dB -30 -40 -50 -60 -70 -30 -40 -50 -60 -80 -70 -90 -100 -50 -40 -30 -20 -10 0 10 20 FREQUENCY - MHz 30 40 -80 50 0 5 10 15 03277- 0- 034 Figure 14. Single Sideband @ 65 MHz, RBW = 50 Hz, fC = 66 MHz, f = 1 MHz, RSET = 10 k (IOUT = 4 mA) 20 25 30 35 FREQUENCY - MHz 40 45 50 03277- 0- 036 Figure 16. 16-QAM @ 42 MHz Spectral Plot, RBW = 1 kHz 0 0 -10 -10 -20 -20 MAGNITUDE - dB MAGNITUDE - dB -30 -40 -50 -60 -70 -30 -40 -50 -60 -80 -70 -90 -100 -2.5 -2.0 -1.5 -1.0 -0.5 0 0.5 1.0 FREQUENCY - MHz 1.5 2.0 -80 2.5 03277- 0- 035 Figure 15. Single Sideband @ 65 MHz, RBW = 10 Hz, fC = 66 MHz, f = 1 MHz, RSET = 10 k (IOUT = 4 mA) 0 5 10 15 20 25 30 35 FREQUENCY - MHz 40 45 Figure 17. 16-QAM @ 5 MHz Spectral Plot, RBW = 1 kHz Rev. 0 | Page 10 of 36 50 03277- 0- 037 AD9878 REGISTER BIT DEFINITIONS Table 3. AD9878 Register Map Address (hex) Bit 7 00 SDIO Bidirectional 01 PLL Lock Detect 02 Power Down PLL Bit 6 Bit 5 LSB First Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 OSC IN Multiplier M[4:0] Reset MCLK Divider R[5:0] Default (hex) Type 0x08 Read/Write 0x00 Read/Write Power Down Reference ADC12A Power Down Reference ADC12B 0x00 Read/Write Flag 1 Flag 0 Enable 0x00 Read/Write 0x00 Read/Write 05 0x00 Read/Write 06 0x00 Read-Only 0x00 Read/Write 0x80 Read/Write 09 0x00 Read/Write 0A 0x00 Read/Write 0B 0x00 Read/Write 0x00 Read/Write 0x00 Read/Write 0x00 Read/Write 0x00 Read/Write Power Down DAC Tx 03 04 Power Down Digital Tx Power Down ADC12A Video Input into ADC12B Flag 2 Flag 0 07 Video Input Enable 08 ADC Clocked Direct from OSCIN Power Down ADC12B Power Down ADC10 Sigma-Delta Output Control Word [7:0] Clamp Level for Vidio Input [6:0] Rx Port Fast Edge Rate Power-Down Reference ADC10 Power Down Rx Sync Gen Send ADC12A Data Only 0C Send ADC12B Data Only Version [3:0] Tx Frequency Tuning Word Profile 1 LSBs [1:0] 0D Tx Frequency Tuning Word Profile 0 LSBs [1:0] DAC Fine Gain Control [3:0] 0E Tx Path Select Profile 1 0F Tx Path AD8321/3 Gain Control Mode Tx Path Bypass sinc-1 Filter Tx Path Spectral Inversion Tx Path Transmit Single Tone 10 Tx Path Frequency Tuning Word Profile 0 [9:2] 0x00 Read/Write 11 Tx Path Frequency Tunin g Word Profile 0 [17:10] 0x00 Read/Write 12 Tx Path Frequency Tuning Word Profile 0 [25:18] 0x00 Read/Write 0x00 Read/Write 13 Cable Driver Amplifier Coarse Gain Control Profile 0 [7:4] Fine Gain Control Profile 0 [3:0] 14 Tx Path Frequency Tu ning Word Profile 1 [9:2] 0x00 Read/Write 15 Tx Path Frequency Tuning Word Profile 1 [17:10] 0x00 Read/Write 16 Tx Path Frequency Tuning Word Profile 1 [25:18] 0x00 Read/Write 0x00 Read/Write 17 Cable Driver Amplifier Coarse Gain Control Profile 1 [7:4] Fine Gain Control Profile 1 [3:0] REGISTER 0--INITIALIZATION Bits 0 to 4: OSCIN Multiplier This register field is used to program the on-chip multiplier (PLL) that generates the chip's high frequency system clock, fSYSCLK. For example, to multiply the external crystal clock fOSCIN by 16 decimal, program Register 0, Bits 4:0 as 0x10. The default value of M is 0x08. Valid entries range from 1 to 31. When M is chosen equal to 1, the PLL is disabled and all internal clocks are derived directly from OSCIN. The PLL requires 200 MCLK cycles to regain frequency lock after a change in M, the clock multiplier value. After the recapture time of the PLL, the frequency of fSYSCLK is stable. Rev. 0 | Page 11 of 36 AD9878 Bit 5: Reset Bit 2: Power-Down ADC10 Writing a 1 to this bit resets the registers to their default values and restarts the chip. The Reset bit always reads back 0. The bits in Register 0 are not affected by this software reset. However, a low level at the RESET pin would force all registers, including all bits in Register 0, to their default state. Active high powers down the 10-bit ADC. Bit 3: Power-Down ADC12B Active high powers down the ADC12B. Bit 4: Power-Down ADC12A Bit 6: LSB First Active high indicates SPI serial port access of instruction byte and data registers is least significant bit (LSB) first. Default low indicates most significant bit (MSB) first format. Active high powers down the ADC12A. Bit 5: Power-Down Tx Active high powers down the digital transmit section of the chip, similar to the function of the PWRDN pin. Bit 7: SDIO Bidirectional Active high configures the serial port as a three signal port with the SDIO pin used as a bidirectional input/output pin. Default low indicates the serial port uses four signals with SDIO configured as an input and SDO configured as an output. Bit 6: Power-Down DAC Tx Active high powers down the DAC. Bit 7: Power-Down PLL REGISTER 1--CLOCK CONFIGURATION Active high powers down the OSCIN multiplier. Bits [5:0]: MCLK Divider. REGISTER 3--FLAG CONTROL This register determines the output clock on the OSCOUT pin. At default 0 (R = 0), OSCOUT provides a buffered version of the OSCIN clock signal for other chips. The register can also be used to divide the chip's master clock fMCLK by R, where R is an integer number between 2 and 63. The generated reference clock on OSCOUT pin can be used for external frequency controlled devices. Bit 0: Flag 0 Enable Active high, the SDELTA pin will maintain a fixed logic level determined directly by the MSB of the sigma-delta control word of Register 4. Bit 1: Flag 1 The logic level of this bit will be applied at the FLAG1 pin. Bit 7: PLL Lock Detect When this bit is set low, the OSCOUT pin functions in its default mode and provides an output clock with frequency fMCKL/R as described above. If this bit is set to 1, the OSCOUT pin is configured to indicate whether the PLL is locked to fOSCIN. In this mode the OSCOUT pin should be low-pass filtered with an RC filter of 1.0 k and 0.1 F. A high output on OSCOUT indicates that the PLL has achieved lock with fOSCIN. Bit 4: Flag 2 The logic level of this bit will be applied at the FLAG2 pin. Bit 5: Video Input into ADC12B If the video input is enabled, setting this bit high sends the signal applied to the VIDEO IN pin to the ADC12B. Otherwise, the signal applied to the VIDEO IN pin is sent to the ADC12A. REGISTER 2--POWER-DOWN Sections of the chip that are not used can be powered down when the corresponding bits are set high. This register has a default value of 0x00; all sections active. Bit 0: Power-Down ADC 12B Voltage Reference Active high powers down the voltage reference circuit for ADC12B. Bit 1: Power-Down ADC12A Voltage Reference REGISTER 4--SIGMA-DELTA CONTROL WORD Bits [7:0]: Sigma-Delta Control Word The sigma-delta control word is 8 bits wide and controls the duty cycle of the digital output on the SIGDELT pin. Changes to the sigma-delta control word take effect immediately for every register write. Sigma-delta output control words have a default value of 0. The control words are in straight binary format with 0x00 corresponding to the bottom of scale or 0% duty cycle, and 0xFF corresponding to the top of scale or near 100% duty cycle. Active high powers down the voltage reference circuit for ADC12A. Rev. 0 | Page 12 of 36 AD9878 Bit 7: Flag 0 (Sigma-Delta Control Word MSB) Bit 7: ADC Clocked Directly from OSCIN When the Flag 0 Enable bit (Register 3, Bit 0) is set, the logic level of this bit will appear on the output of the SIGDELT pin. When set high, the ADC sampling clock is derived directly from the input clock at OSCIN. In this mode, the clock supplied to the OSCIN pin should originate from an external crystal or low jitter crystal oscillator. When this bit is low, the ADC sampling clock is derived from the internal PLL and the frequency of the clock is equal to fOSCIN x M/8. REGISTER 07--VIDEO INPUT CONFIGURATION Bits [6:0]: Clamp Level Control Value The 7-bit clamp level control value is used to set an offset to the automatic clamp level control loop. The actual ADC output will have a clamp level offset equal to 16 times the clamp level control value as shown: REGISTER C--DIE REVISION Bits [3:0]: Version The die version of the chip can be read from this register. Clamp Level Offset Clamp Level Control Value = (x)16 The default value for the clamp level control value is 0x20. This results in an ADC output clamp level offset of 512 LSBs. The valid programming range for the clamp level control value is from 0x16 to 0x127. REGISTER 8--ADC CLOCK CONFIGURATION REGISTER D--Tx FREQUENCY TUNING WORDS LSBS This register accommodates the two least significant bits each for both of the frequency tuning words. See the description of the burst parameter below. REGISTER E--DAC GAIN CONTROL Bit 0: Send ADC12B Data Only When this bit is set high, the device enters a nonmultiplexed mode and only the data from the ADC12B will be sent to the IF[11:0] digital output port. Bit 1: Send ADC12A Data Only When this bit is set high, the device enters a nonmultiplexed mode and only the data from the ADC12A will be sent to the IF[11:0] digital output port. Note: If both the Send ADC12B Data Only and Send ADC12A Data Only register bits are set high, the device will send both ADC12A and ADC12B data in multiplexed mode. This register allows the user to program the DAC gain if the TxGain Control Select Bit 3 in Register F is set to 0. Bits [3:0] 0000 0001 0010 0011 ... 1110 1111 DAC Gain (dB) 0.0 (default) 0.5 1.0 1.5 ... 7.0 7.5 REGISTER F--Tx PATH CONFIGURATION Bit 3: Power-Down ADC10 Voltage Reference Bit 0: Single Tone Tx Mode Active high powers down the voltage reference circuit for ADC10. Active high configures the AD9878 for single-tone applications (e.g., FSK). The AD9878 will supply a single frequency output as determined by the frequency tuning word selected by the active profile. In this mode, the TxIQ input data pins are ignored but should be tied to a valid logic voltage level. Default value is 0 (inactive). Bit 4: Power Down RxSYNC Generator Setting this bit to 1 powers down the 10-bit ADC's sampling clock and makes the RxSYNC output pin stay low. It can be used for additional power saving on top of the power-down selections in Register 2. Bit 1: Spectral Inversion Tx When set to 1, inverted modulation is performed: Bit 5: Rx PORT Fast Edge Rate Setting this bit to 1 increases the output drive strength of all digital output pins except MCLK, REFCLK, SIGDELT, and FLAG[2:1]. These pins always have high output drive capability. MODULATOR_OUT = [I cos (t) + Q sin (t)]. Default is logic 0, non-inverted modulation: MODULATOR_OUT = [I cos (t) - Q sin (t)]. Rev. 0 | Page 13 of 36 AD9878 Bit 2: Bypass Inv Sinc Tx Filter default mode, the complete 8-bit register value is transmitted over the 3-wire cable amplifier (CA) interface. If Bit 3 of Register F is set high, Bits [7:4] of Registers 0x13 and 0x17 will determine the 8-bit word sent over the CA interface according to the table below: Active high, configures the AD9878 to bypass the sin(x)/x compensation filter. Default value is 0 (inverse sinc filter enabled). Bit 3: CA Interface Mode Select This bit changes the manner in which transmit gain control is performed. Typically either AD8321/AD8323 (default 0) or AD8322/AD8327 (1) variable gain cable amplifiers are programmed over the chip's 3-wire CA interface. The Tx Gain Control Select changes the interpretation of the bits in Registers 13, 17, 1B, and 1F. See the Cable Driver Gain Control section below. Bit 5: Profile Select The AD9878 quadrature digital upconverter is capable of storing two preconfigured modulation modes called profiles. Each profile defines a transmit frequency tuning word and cable driver amplifier gain (/DAC gain) setting. The Profile Select bit or PROFILE pin programs the current register profile to be used. The Profile Select bit should always be 0 if the PROFILE pin is used to switch between profiles. Using the Profile Select bit as a means of switching between different profiles requires the PROFILE pin to be tied low. REGISTERS 10 THROUGH 17: BURST PARAMETER Tx Frequency Tuning Words The frequency tuning word (FTW) determines the DDS generated carrier frequency (fC) and is formed via a concatenation of register addresses. Bits [7:4] 0000 0001 0010 0011 0100 0101 0110 0111 1000 CA Interface Transmit Word 0000 0000 (default) 0000 0001 0000 0010 0000 0100 0000 1000 0001 0000 0010 0000 0100 0000 1000 0000 In this mode the lower bits of Registers 0x13 and 0x17 determine the fine gain setting of the DAC output: Bits [3:0] 0000 0001 0010 0011 ... 1110 1111 DAC Fine Gain (dB) 0.0 (default) 0.5 1.0 1.5 ... 7.0 7.5 New data is automatically sent over the 3-wire CA interface (and DAC gain adjust) whenever the value of the active gain control register changes or a new profile is selected. The default value is 0x00 (lowest gain). The formula for the combined output level calculation of AD9878 fine gain and AD8327 or AD8322 coarse gain is: The 26-bit FTW is spread over four register addresses. Bit 25 is the MSB and Bit 0 is the LSB. The carrier frequency equation is given as: fC = (FTW x fSYSCLK)/226 V8327 = V9878(0) + (fine)/2 + (coarse) - 19 V8322 = V9878(0) + (fine)/2 + (coarse) - 14 where: where : fine = decimal value of Bits [3:0] fSYSCLK = M x fOSCIN , and FTW < 0x2000 coarse = decimal value of Bits [7:4] Changes to FTW bytes take effect immediately. V9878(0): Level at AD9878 output in dBmV for fine = 0. Cable Driver Gain Control V8327: Level at output of AD8327 in dBmV. The AD9878 has a 3-pin interface to the AD832x family of programmable gain cable driver amplifiers. This allows direct control of the cable driver's gain through the AD9878. In its V8322: Level at output of AD8322 in dBmV. Rev. 0 | Page 14 of 36 AD9878 SERIAL INTERFACE FOR REGISTER CONTROL The AD9878 serial port is a flexible, synchronous serial communications port that allows easy interface to many industry standard microcontrollers and microprocessors. The interface allows read/write access to all registers that configure the AD9878. Single or multiple byte transfers are supported. Also, the interface can be programmed to read words either MSB first or LSB first. The AD9878's serial interface port I/O can be configured to have one bidirectional I/O (SDIO) pin or two unidirectional I/O (SDIO/SDO) pins. General Operation of the Serial Interface There are two phases to a communication cycle with the AD9878. Phase 1 is the instruction cycle, which is the writing of an instruction byte into the AD9878, coincident with the first eight SCLK rising edges. The instruction byte provides the AD9878 serial port controller with information regarding the data transfer cycle, which is Phase 2 of the communication cycle. The Phase 1 instruction byte defines whether the upcoming data transfer is read or write, the number of bytes in the data transfer, and the starting register address for the first byte of the data transfer. The first eight SCLK rising edges of each communication cycle are used to write the instruction byte into the AD9878. Table 4. N1 0 0 1 N0 0 1 0 Description Transfer 1 Byte Transfer 2 Bytes Transfer 3 Bytes 1 1 Transfer 4 Bytes The Bits [A4:A0] determine which register is accessed during the data transfer portion of the communications cycle. For multibyte transfers, this address is the starting byte address. The remaining register addresses are generated by the AD9878. tDS tSCLK CS tPWH tPWL SCLK tDS SDIO tDH INSTRUCTION BIT 7 INSTRUCTION BIT 6 03277- 0- 005 Figure 18. Timing Diagram for Register Write CS SCLK tDV SDIO SDO DATA BIT N DATA BIT N 03277- 0- 006 The eight remaining SCLK edges are for Phase 2 of the communication cycle. Phase 2 is the actual data transfer between the AD9878 and the system controller. Phase 2 of the communication cycle is a transfer of 1 to 4 data bytes as determined by the instruction byte. Normally, using one multibyte transfer is the preferred method. However, single-byte data transfers are useful to reduce CPU overhead when register access requires one byte only. Registers change immediately upon writing to the last bit of each transfer byte. SCLK--Serial Clock. The serial clock pin is used to synchronize data transfers from the AD9878 and to run the serial port state machine. The maximum SCLK frequency is 15 MHz. Input data to the AD9878 is sampled on the rising edge of SCLK. Output data changes on the falling edge of SCLK. Instruction Byte CS--Chip Select. Active low input starts and gates a 16 N1 15 N0 14 A4 13 A3 12 A2 11 A1 Serial Interface Port Pin Description communication cycle. It allows multiple devices to share a common serial port bus. The SDO and SDIO pins go to a high impedance state when CS is high. Chip select should stay low during the entire communication cycle. The instruction byte contains the following information: MSB 17 R/W Figure 19. Timing Diagram for Register Read LSB 10 A0 SDIO--Serial Data I/O. Data is always written into the AD9878 The R/W bit of the instruction byte determines whether a read or a write data transfer will occur after the instruction byte write. Logic high indicates a read operation. Logic low indicates a write operation. The [N1:N0] bits determine the number of bytes to be transferred during the data transfer cycle. The bit decodes are shown in Table 4. The timing diagrams are shown in Figure 18 and Figure 19. on this pin. However, this pin can be used as a bidirectional data line. The configuration of this pin is controlled by Bit 7 of Register 0. The default is Logic 0, which configures the SDIO pin as unidirectional. SDO--Serial Data Out. Data is read from this pin for protocols that use separate lines for transmitting and receiving data. In the case where the AD9878 operates in a single bidirectional I/O mode, this pin does not output data and is set to a high impedance state. Rev. 0 | Page 15 of 36 AD9878 MSB/LSB Transfers Notes on Serial Port Operation The AD9878 serial port can support most significant bit (MSB) first or least significant bit (LSB) first data formats (see Figure 20 and Figure 21). This functionality is controlled by the LSB First bit in Register 0. The default mode is MSB First. When this bit is set active high, the AD9878 serial port is in LSB First format. In LSB First mode, the instruction byte and data bytes must be written from the least significant bit to the most significant bit. In LSB First mode, the serial port internal byte address generator increments for each byte of the multibyte communication cycle. The AD9878 serial port configuration bits reside in Bits 6 and 7 of Register Address 0x00. It is important to note that the configuration changes immediately upon writing to the last bit of the register. For multibyte transfers, writing to this register may occur during the middle of the communication cycle. Measures must be taken to compensate for this new configuration for the remaining bytes of the current communication cycle. INSTRUCTION CYCLE CS DATA TRANSFER CYCLE SCLK SDIO R/W N1 N0 A4 A3 A2 A1 SDO A0 D7n D6n D20 D10 D00 D7n D6n D20 D10 D00 03277- 0- 003 Figure 20. Serial Register Interface Timing, MSB First INSTRUCTION CYCLE CS DATA TRANSFER CYCLE SCLK SDIO SDO A0 A1 A2 A3 A4 N0 N1 R/W D00 D10 D20 D6n D7n D00 D10 D20 D6n D7n The same considerations apply when setting the Reset bit in Register Address 0x00. All other registers are set to their default values, but the software reset does not affect the bits in Register Address 0x00. It is recommended to use only single-byte transfers when changing serial port configurations or initiating a software reset. A write to Bits 1, 2, and 3 of Address 0x00 with the same logic levels as Bits 7, 6, and 5 (bit pattern: XY1001YX binary) allows the user to reprogram a lost serial port configuration and to reset the registers to their default values. A second write to Address 0x00 with the Reset bit low and the serial port configuration as specified above (XY), reprograms the OSCIN multiplier setting. A changed fSYSCLK frequency is stable after a maximum of 200 fMCLK cycles (wake-up time). 03277- 0- 004 Figure 21. Serial Register Interface Timing, LSB First When this bit is set default low, the AD9878 serial port is in MSB First format. In MSB First mode, the instruction byte and data bytes must be written from the most significant bit to the least significant bit. In MSB First mode, the serial port internal byte address generator decrements for each byte of the multibyte communication cycle. When incrementing from 0x1F, the address generator changes to 0x00. When decrementing from 0x00, the address generator changes to 0x1F. Rev. 0 | Page 16 of 36 AD9878 THEORY OF OPERATION For a general understanding of the AD9878, refer to Figure 22, a block diagram of the device architecture. The device consists of a transmit path, receive path, and auxiliary functions, such as a PLL, a sigma-delta DAC, a serial control port, and a cable amplifier interface. The 12-bit and 10-bit IF ADCs can convert direct IF inputs up to 70 MHz and run at sample rates up to 33 MSPS. A video input with an adjustable signal clamping level along with the 10-bit ADC allow the AD9878 to process an NTSC and a QAM channel simultaneously. The transmit path contains an interpolation filter, a complete quadrature digital up-converter, an inverse sinc filter, and a 12-bit current output DAC. The programmable sigma-delta DAC can be used to control external components, such as variable gain amplifiers (VGAs) or voltage controlled tuners. The CAPORT provides an interface to the AD8321/AD8323 or AD8322/AD8327 programmable gain amplifier (PGA) cable drivers, enabling host processor control via the MxFE serial port (SPORT). The receive path contains a 10-bit ADC and a dual 12-bit ADC. All internally required clocks and an output system clock are generated by the PLL from a single crystal or clock input. AD9878 DATA ASSEMBLER TxIQ 6 I 12 QUADRATURE MODULATOR DAC GAIN CONTROL CIC LPF FIR LPF 12 4 COS 4 SINC-1 TxSYNC Q 12 12 4 4 MUX 12 Tx DAC (fSYSCLK) SIN (fIQCLK) FSADJ SINC-1 BYPASS (fOSCIN) DDS PLL OSCIN x M /4 XTAL MCLK CA_PORT 3 4 /4 OSCIN - INPUT REG CA INTERFACE 5 RxSYNC IF10 /2 /2 10 /2 (fOSCIN) IF12[11:0] IF12 F10 INPUT ADC MUX Rx PORT 12 -_OUT - FLAG1 SERIAL INTERFACE (fOSCIN) IF10[4:0] 12 /8 PROFILE SELECT PROFILE SPORT (fMCLK) /R REFCLK 12 IF12B INPUT MUX ADC VIDEO INPUT MUX 12 - MUX ADC IF12A INPUT + CLAMP LEVEL DAC 03277- 0- 007 Figure 22. AD9878 Block Diagram Rev. 0 | Page 17 of 36 AD9878 tSU MC L K tHU T x SYN C Tx IQ TxI [ 11: 6] TxI [ 5: 0] TxQ [ 11: 6] TxQ [ 5: 0] TxI [ 11: 6] ' TxI [ 5: 0] ' TxQ [ 11: 6] ' TxQ [ 5: 0] ' TxI [ 11: 6] ' ' TxI [ 5: 0] ' ' 03277- 0-008 Figure 23. Tx Timing Diagram Transmit Path INTERPOLATION FILTER The transmit path contains an interpolation filter, a complete quadrature digital up-converter, an inverse sinc filter, and a 12-bit current output DAC. The maximum output current of the DAC is set by an external resistor. The Tx output PGA provides additional transmit signal level control. The transmit path interpolation filter provides an up-sampling factor of 16 with an output signal bandwidth as high as 5.8 MHz. Carrier frequencies up to 65 MHz with 26 bits of frequency tuning resolution can be generated by the direct digital synthesizer (DDS). The transmit DAC resolution is 12 bits and it can run at sampling rates up to 232 MSPS. Analog output scaling from 0 dB to 7.5 dB in 0.5 dB steps is available to preserve SNR when reduced output levels are required. Once through the Data Assembler, the IQ data streams are fed through a 4x FIR low-pass filter and a 4x Cascaded Integrator Comb (CIC) low-pass filter. The combination of these two filters results in the sample rate increasing by a factor of 16x. In addition to the sample rate increase, the half-band filters provide the low-pass filtering characteristic necessary to suppress the spectral images between the original sampling frequency and the new (16x higher) sampling frequency. DATA ASSEMBLER HALF-BAND FILTERS (HBFs) HBF 1 and HBF 2 are both interpolating filters, each of which doubles the sampling rate. Together, HBF 1 and HBF 2 have 26 taps and provide a factor of four increase in the sampling rate (4 x fIQCLK or 8 x fNYQ). The AD9878 data path operates on two 12-bit words, the I and Q components, that form a complex symbol. The data assembler builds the 24-bit complex symbols from four consecutive 6-bit words read over the TxIQ [5:0] bus. These words are strobed into the data assembler synchronous to the master clock (MCLK). A high level on TxSYNC signals the start of a transmit symbol. The first two 6-bit words of the symbol form the I component; the second two 6-bit words form the Q component. Symbol components are assumed to be in twos complement format. The timing of the interface is fully described in the Transmit Timing section. The I/Q sample rate fIQCLK puts a bandwidth limit on the maximum transmit spectrum. This is the familiar Nyquist limit (hereafter referred to as fNYQ) and is equal to one-half fIQCLK. In relation to phase response, both HBFs are linear phase filters. As such, virtually no phase distortion is introduced within the pass band of the filters. This is an important feature, as phase distortion is generally intolerable in a data transmission system. TRANSMIT TIMING The combined frequency response of the HBF and CIC filters puts a limit on the input signal bandwidth that can be propagated through the AD9878.The usable bandwidth of the filter chain puts a limit on the maximum data rate that can be propagated through the AD9878. A look at the pass-band detail of the combined filter response (Figure 24) indicates that in order to maintain an amplitude error of no more than 1 dB, signal bandwidth is restricted to no more than about 60% of fNYQ. Thus, in order to keep the bandwidth of the data in the flat portion of the filter pass band, the user must oversample the The AD9878 provides a master clock MCLK and expects 6-bit multiplexed TxIQ data on each rising edge (see Figure 23). Transmit symbols are framed with the TxSYNC input. TxSYNC high indicates the start of a transmit symbol. Four consecutive 6-bit data packages form a symbol (I MSB, I LSB, Q MSB, and Q LSB). CASCADED INTEGRATOR COMB (CIC) FILTER The CIC filter is configured as a programmable interpolator and provides a sample rate increase by a factor of 4. The frequency response of the CIC filter is given by: 1 1-e H (f ) = 4 - j (2f ( 4 )) 3 1-e j 2f = 1 sin(4f ) 4 sin(f ) 3 COMBINED FILTER RESPONSE Rev. 0 | Page 18 of 36 AD9878 baseband data by at least a factor of two prior to presenting it to the AD9878. Note that without oversampling, the Nyquist bandwidth of the base-band data corresponds to fNYQ. As such, the upper end of the data bandwidth will suffer 6 dB or more of attenuation due to the frequency response of the digital filters. Furthermore, if the baseband data applied to the AD9878 has been pulse shaped, there is an additional concern. Typically, pulse shaping is applied to the baseband data via a filter having a raised cosine response. In such cases, an value is used to modify the bandwidth of the data where the value of is such that: 0 < < 1. A value of 0 causes the data bandwidth to correspond to the Nyquist bandwidth. A value of 1 causes the data bandwidth to be extended to twice the Nyquist bandwidth. Thus, with 2x oversampling of the baseband data and = 1, the Nyquist bandwidth of the data will correspond with the I/Q Nyquist bandwidth. As stated earlier, this results in problems near the upper edge of the data bandwidth due to the frequency response of the filters. The maximum value of that can be implemented is 0.45. This is because the data bandwidth becomes: DIGITAL UPCONVERTER The digital quadrature modulator stage following the CIC filters is used to frequency shift (upconvert) the baseband spectrum of the incoming data stream up to the desired carrier frequency. The carrier frequency is controlled numerically by a direct digital synthesizer (DDS). The DDS uses the internal system clock (fSYSCLK) to generate the desired carrier frequency with a high degree of precision. The carrier is applied to the I and Q multipliers in quadrature fashion (90 phase offset) and summed to yield a data stream that is the modulated carrier. The modulated carrier becomes the 12-bit sample sent to the DAC. Tx SIGNAL LEVEL CONSIDERATIONS The quadrature modulator itself introduces a maximum gain of 3 dB in signal level. To visualize this, assume that both the I data and Q data are fixed at the maximum possible digital value, x. Then the output of the modulator, z, is z = [x cos(t ) - x sin(t )] Q X 1 / 2 (1 + )f NYQ = 0.725f NYQ Z X I which puts the data bandwidth at the extreme edge of the flat portion of the filter response. 03277- 0- 010 If a particular application requires an value between 0.45 and 1, then the user must oversample the baseband data by at least a factor of four. Over the frequency range of the data to be transmitted, the combined HB1, HB2, and CIC filter introduces a worst-case droop of less than 0.2 dB. 1 0 Figure 25. 16-Quadrature Modulation It can be shown that |z| assumes a maximum value of z = x 2 + x 2 = x 2 (a gain of +3 dB). However, if the same number of bits were used to represent the |z| values that were used to represent the x values, an overflow would occur. To prevent this possibility, an effective -3 dB attenuation is internally implemented on the I and Q data path: z = 1/ 2 + 1/ 2 = x MAGNITUDE - dB -1 -2 The following example assumes a PK/rms level of 10 dB: -3 Maximum Symbol Component Input Value = 2047 LSBs - 0.2 dB = 2000 LSBs -4 Maximum Complex Input RMS Value = -5 -6 2000 LSBs 6 dB - Pk rms (dB) = 1265 LSBs rms 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 FREQUENCY RELATIVE TO I/Q NYQ BW 0.9 1.0 03277- 0- 009 Figure 24. Cascaded Filter Pass Band The maximum complex input rms value calculation uses both I and Q symbol components that add a factor of 2 (= 6 dB) to the formula. Table 5 shows typical I-Q input test signals with amplitude levels related to 12-bit full scale (FS). Rev. 0 | Page 19 of 36 AD9878 Table 5. I-Q Input Test Signals Analog Output Single Tone (fC - f) Single Tone (fC + f) Dual Tone (fC f) Digital Input I = cos(f) Q = cos(f + 90) = -sin(f) I = cos(f) Q = cos(f + 270) = +sin(f) I = cos(f) FS - 0.2 dB FS Q = cos(f + 180) = -cos(f) or Q = +cos(f) then RSET = (39.4/0.02), or approximately 2 k. Modulator Output Input Level Level FS - 0.2 dB FS - 3.0 dB FS - 0.2 dB The following equation calculates the full-scale output current including the programmable DAC gain control. IOUT = 39.4/RSET x 10(-7.5 + 0.5NGAIN)/20 where NGAIN is the value of DAC Fine Gain Control[3:0]. FS - 0.2 dB FS - 0.2 dB FS - 3.0 dB FS - 0.2 dB FS - 0.2 dB FS Tx THROUGHPUT AND LATENCY Data inputs affect the output fairly quickly but remain effective due to the AD9878's filter characteristics. Data transmit latency through the AD9878 is easiest to describe in terms of fSYSCLK clock cycles (4 x fMCLK). The numbers quoted are when an effect is first seen after an input value change. Latency of I/Q data entering the data assembler (AD9878 input) to the DAC output is 119 fSYSCLK clock cycles (29.75 fMCLK cycles). DC values applied to the data assembler input will take up to 176 fSYSCLK clock cycles (44 fMCLK cycles) to propagate and settle at the DAC output. Frequency hopping is accomplished via changing the PROFILE input pin. The time required to switch from one frequency to another is less than 232 fSYSCLK cycles (58.5 fMCLK cycles). D/A CONVERTER A 12-bit digital-to-analog converter (DAC) is used to convert the digitally processed waveform into an analog signal. The worst-case spurious signals due to the DAC are the harmonics of the fundamental signal and their aliases (see the Analog Devices DDS Tutorial at www.analog.com/dds). The conversion process will produce aliased components of the fundamental signal at n x fSYSCLK fCARRIER (n = 1, 2, 3). These are typically filtered with an external RLC filter at the DAC output. It is important for this analog filter to have a sufficiently flat gain and linear phase response across the bandwidth of interest so as to avoid modulation impairments. A relatively inexpensive seventh order elliptical low-pass filter is sufficient to suppress the aliased components for HFC network applications. The full-scale output current range of the AD9878 is 4 mA to 20 mA. Full-scale output currents outside of this range will degrade SFDR performance. SFDR is also slightly affected by output matching; that is, the two outputs should be terminated equally for best SFDR performance. The output load should be located as close as possible to the AD9878 package to minimize stray capacitance and inductance. The load may be a simple resistor to ground, an op amp current-to-voltage converter, or a transformer-coupled circuit. It is best not to attempt to directly drive highly reactive loads, such as an LC filter. Driving an LC filter without a transformer requires that the filter be doubly terminated for best performance; that is, the filter input and output should both be resistively terminated with the appropriate values. The parallel combination of the two terminations will determine the load that the AD9878 sees for signals within the filter pass band. For example, a 50 terminated input/output low-pass filter will look like a 25 load to the AD9878. The output compliance voltage of the AD9878 is -0.5 V to +1.5 V. Any signal developed at the DAC output should not exceed +1.5 V; otherwise signal distortion will result. Furthermore, the signal may extend below ground as much as 0.5 V without damage or signal distortion. The AD9878 true and complement outputs can be differentially combined for common-mode rejection using a broadband 1:1 transformer. Using a grounded center tap results in signals at the AD9878 DAC output pins that are symmetrical about ground. As previously mentioned, by differentially combining the two signals, the user can provide some degree of common-mode signal rejection. A differential combiner might consist of a transformer or an op amp. The object is to combine or amplify only the difference between two signals and to reject any common--usually undesirable--characteristic, such as 60 Hz hum or clock feedthrough that is equally present on both individual signals. The AD9878 provides true and complement current outputs. The full-scale output current is set by the RSET resistor at Pin 49 and the DAC Gain register. Assuming maximum DAC gain, the value of RSET for a particular full-scale IOUT is determined using the equation: RSET = 32 VDACRSET/IOUT = 39.4/IOUT AD9878 DAC AD832x Tx CA LOW-PASS FILTER 75 3 CA_EN CA_DATA CA_CLK VARIABLE GAIN CABLE DRIVER AMPLIFIER 03277- 0- 011 For example, if a full-scale output current of 20 mA is desired, Rev. 0 | Page 20 of 36 Figure 26. Cable Amplifier Connection AD9878 Connecting the AD9878 true and complement outputs to the differential inputs of the programmable gain cable drivers AD8321/AD8323 or AD8322/AD8327 (see Figure 26) provides an optimized solution for the standard compliant cable modem upstream channel. The cable driver's gain can be programmed through a direct 3-wire interface using the AD9878's profile registers. PROGRAMMING THE AD8321/AD8323 OR AD8322/AD8327 CABLE DRIVER AMPLIFIER Programming the gain of the AD832x family of cable driver amplifiers can be accomplished via the AD9878 cable amplifier control interface. Two 8-bit registers within the AD9878 (one per profile) store the gain value to be written to the serial 3-wire port. Typically, either the AD8321/AD8323 or AD8322/AD8327 variable gain cable amplifiers are connected to the chip's 3-wire cable amplifier interface. The Tx Gain Control Select bit in Register 0x0F changes the interpretation of the bits in Registers 0x13, 0x17, 0x1B, and 0x1F. See Figure 27 and Cable Driver Gain Control Register description. 8 tMCLK 8 tMCLK CA ENABLE 8 tMCLK 4 tMCLK 4 tMCLK MSB OSCIN CLOCK MULTIPLIER The AD9878 can accept either an input clock into the OSCIN pin or a fundamental mode crystal across the OSCIN and XTAL pins as the device's main clock source. The internal PLL then generates the fSYSCLK signal from which all other internal signals are derived. The DAC uses fSYSCLK as its sampling clock. For DDS applications, the carrier is typically limited to about 30% of fSYSCLK. For a 65 MHz carrier, the system clock required is above 216 MHz. The OSCIN multiplier function maintains clock integrity as evidenced by the AD9878 system's excellent phase noise characteristics and low clock-related spur in the output spectrum. External loop filter components consisting of a series resistor (1.3 k) and capacitor (0.01 F) provide the compensation zero for the OSCIN multiplier PLL loop. The overall loop performance has been optimized for these component values. CA_CLK CA_DATA with the current profile to the AD832x whenever the selected AD9878 cable driver amplifier gain setting is changed. Once a new stable gain value has been detected (48 to 64 MCLK cycles after initiation) data write starts with CA_EN going low. The AD9878 will always finish a write sequence to the cable driver amplifier once it is started. The logic controlling data transfers to the cable driver amplifier uses up to 200 MCLK cycles and has been designed to prevent erroneous write cycles from ever occurring. LSB 03277- 0- 012 Figure 27. Cable Amplifier Interface Timing Data transfers to the programmable gain cable driver amplifier are initiated by four conditions: 1. Power-Up and Hardware Reset--Upon initial power-up and every hardware reset, the AD9878 clears the contents of the Gain Control registers to 0, which defines the lowest gain setting of the AD832x. Thus, the AD9878 writes all 0s out of the 3-wire cable amplifier control interface. 2. Software Reset--Writing a 1 to Bit 5 of Address 0x00 initiates a software reset. On a software reset, the AD9878 clears the contents of the Gain Control registers to 0 for the lowest gain and sets the Profile Select to 0. The AD9878 writes all 0s out of the 3-wire cable amplifier control interface if the gain was on a different setting (different from 0) before. 3. Change in Profile Selection--The AD9878 samples the PROFILE input pin together with the two Profile Select bits and writes to the AD832x Gain Control registers when a change in profile and gain is determined. The data written to the cable driver amplifier comes from the AD9878 Gain Control register associated with the current profile. 4. Write to the AD9878 Cable Driver Amplifier Control Registers--The AD9878 will write gain control data associated CLOCK AND OSCILLATOR CIRCUITRY The AD9878's internal oscillator generates all sampling clocks from a simple, low cost, parallel resonance, fundamental frequency quartz crystal. Figure 28 shows how the quartz crystal is connected between OSCIN (Pin 61) and XTAL (Pin 60) with parallel resonant load capacitors as specified by the crystal manufacturer. The internal oscillator circuitry can also be overdriven by a TTL level clock applied to OSCIN with XTAL left unconnected. fOSCIN = fMCLK x M An internal phase-locked loop (PLL) generates the DAC sampling frequency, fSYSCLK, by multiplying the OSCIN frequency by M. The MCLK signal (Pin 23), fMCLK, is derived by dividing fSYSCLK by 4. fSYSCLK = fOSCIN x M fMCLK = fOSCIN x M/4 An external PLL loop filter (Pin 57) consisting of a series resistor and ceramic capacitor (Figure 28: R1 = 1.3 k, C12 = 0.01 F) is required for stability of the PLL. Also, a shield surrounding these components is recommended to minimize external noise coupling into the PLL's voltage controlled oscillator input (guard trace connected to AVDDPLL). Rev. 0 | Page 21 of 36 AD9878 Figure 22 shows that ADCs are either sampled directly by a low jitter clock at OSCIN or by a clock that is derived from the PLL output. Operating modes can be selected in Register 8. Sampling the ADCs directly with the OSCIN clock requires MCLK programmed to be twice the OSCIN frequency. PROGRAMMABLE CLOCK OUTPUT REFCLK The AD9878 provides an auxiliary output clock on Pin 69, REFCLK. The value of the MCLK divider bit field, R, determines its output frequency as shown in the equations fREFCLK = fMCLK/R, for R = 2 to 63 fREFCLK = fOSCIN, for R = 0 In its default setting (0x00 in Register 1), the REFCLK pin provides a buffered output of fOSCIN. CP2 10F C4 C5 0.1F 0.1F CP1 10F C6 0.1F C1 C2 0.1F 0.1F C3 0.1F AVDD AGND VIDEO IN AGND IF12A+ IF12A- AGND AVDD REFT12A REFB12A AVDD AGND IF12B+ IF12B- AGND AVDD REFT12B REFB12B AVDD AGND AVDD10 AGND10 IF10+ IF10- AGND CP1 10F 100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76 C1 C2 0.1F 0.1F DRGND 1 75 REFT10 DRVDD 2 74 REFB10 (MSB) IF12(11) 3 73 AGND10 IF12(10) 4 72 AVDD10 IF12(9) 5 71 DRVDD IF12(8) 6 70 DRGND IF12(7) 7 69 REFCLK IF12(6) 8 68 SIGDELT IF12(5) 9 67 FLAD(0) IF12(4) 10 66 FLAG(1) IF12(3) 11 65 CA_EN 64 CA_DATA 63 CA_CLK 62 DVDDOSC (MSB) IF10(4) 15 61 OSCIN IF10(3) 16 60 XTAL IF10(2) 17 59 DGNDOSC IF10(1) 18 58 AGNDPLL IF10(0) 19 57 PLLFILT RxSYNC 20 56 AVDDPLL DRGND 21 55 DVDDPLL DRVDD 22 54 DGNDPLL MCLK 23 53 AVDDTx DVDD 24 52 Tx+ DGND 25 51 Tx- AD9878 IF12(2) 12 TOP VIEW (Not to Scale) 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 TxSYNC (MSB) TxIQ(5) TxIQ(4) TxIQ(3) TxIQ(2) TxIQ(1) TxIQ(0) DVDD DGND DVDD DGND PROFILE RESET DVDD DGND SCLK CS SDIO SDO DGNDTx DVDDTx PWRDN REFIO FSADJ IF12(0) 14 C13 0.1F C10 20pF C11 20pF GUARD TRACE C12 R1 1.3k 0.01F 50 AGNDTx IF12(1) 13 C3 0.1F RSET 4.02 03277- 0- 013 Figure 28. Basic Connection Diagram Rev. 0 | Page 22 of 36 AD9878 RESET AND TRANSMIT POWER-DOWN Figure 30). This avoids unintended DAC output samples caused by the transmit path latency and filter settling time. POWER-UP SEQUENCE Software Power-Down Digital Tx (Bit 5 in Register 0x02) is functionally equivalent to the hardware PWRDN pin and takes effect immediately after the last register bit has been written over the serial port. On initial power-up, the RESET pin should be held low until the power supply is stable (see Figure 29). Once RESET is deasserted, the AD9878 can be programmed over the serial port. The on-chip PLL requires a maximum of 1 ms after the rising edge of RESET or a change of the multiplier factor (M) to completely settle. It is recommended that the PWRDN pin be held low during the reset and PLL settling time. Changes to ADC Clock Select (Register 0x08) or Sys Clock Divider N (Register 0x01) should be programmed before the rising edge of PWRDN. Once the PLL is frequency locked and after the PWRDN pin is brought high, transmit data can be sent reliably. If the PWRDN pin cannot be held low throughout the reset and PLL settling time period, then the Power-Down Digital Tx bit or the PWRDN pin should be pulsed after the PLL has settled. This will ensure correct transmit filter initialization. PWRDN 5MCLK MIN. 20 NULL SYMBOLS TxIQ 0 0 0 DATA SYMBOLS 20 NULL SYMBOLS 0 0 0 0 0 TxSYNC 03277-0-015 Figure 30. Timing Sequence to Flush Tx Data Path SIGMA-DELTA OUTPUTS The AD9878 contains an on-chip sigma-delta output that provides a digital logic bit stream with an average duty cycle that varies between 0% and (4095/4096)%, depending on the programmed code, as shown in Figure 31. 8 tMCLK VS 4096 x 8 tMCLK 000h RESET 001h 1ms MIN. 002h 5MCLK MIN. PWRDN 800h 03277- 0- 014 FFFh Figure 29. Power-Up Sequence for Tx Data Path 4096 x 8 tMCLK RESET 8 tMCLK 03277- 0- 016 To initiate hardware reset, the RESET pin should be held low for at least 100 ns. All internally generated clocks except OSCOUT stop during reset. The rising edge of RESET resets the PLL clock multiplier and reinitializes the programmable registers to their default values. The same sequence as described above in the Power-Up Sequence section should be followed after a reset or change in M. Figure 31. Sigma-Delta Output Signals This bit stream can be low-pass filtered to generate a programmable dc voltage of: VDC = [(Sigma-Delta Code/4096) x VH]+ VL where: A software reset (writing a 1 into Bit 5 of Register 0x00) is functionally equivalent to the hardware reset but does not force Register 0x00 to its default value. VH = VDRVDD - 0.6 V TRANSMIT POWER-DOWN In cable modem set-top box applications, the output can be used to control external variable gain amplifiers or RF tuners. A simple single-pole RC low-pass filter provides sufficient filtering (see Figure 32). A low level on the PWRDN pin stops all clocks linked to the digital transmit data path and resets the CIC filter. Deasserting PWRDN reactivates all clocks. The CIC filter is held in a reset state for 80 MCLK cycles after the rising edge of PWRDN to allow for flushing of the half-band filters with new input data. Transmit data bursts should be padded with at least 20 symbols of null data directly before the PWRDN pin is deasserted. Immediately after the PWRDN pin is deasserted, the transmit burst should start with a minimum of 20 null data symbols (see VL = 0.4 V Rev. 0 | Page 23 of 36 AD9878 AD9878 CONTROL WORD MCLK DAC 12 R - DC (VL TO VH) C /8 TYPICAL: R = 50k C = 0.01F f-3dB = 1/(2RC) = 318Hz 03277- 0-017 Figure 32. Sigma-Delta RC Filter In more demanding applications where additional gain, level shift, or drive capability is required, a first or second order active filter might be considered (see Figure 33). R1 R SIGMA-DELTA VOUT R - VSD C R The IF ADCs have differential analog inputs labeled IF+ and IF-. The signal input, VAIN, is the voltage difference between the two input pins, VAIN = VIF+ - VIF-. The full-scale input voltage range is determined by the internal reference voltages, REFT and REFB, which define the top and bottom of the scale. The peak input voltage to the ADC is the difference between REFT and REFB, which is 1 VPD. This results in the ADC full scale input voltage range of 2 VPPD. The digital output code is straight binary and is illustrated in Table 6. Table 6 IF12[11:0] 111...111 111...111 111...110 ... 100...001 100...000 011...111 ... 000...001 000...000 000...000 C AD9878 INPUT SIGNAL RANGE AND DIGITAL OUTPUT CODES OP250 VOFFSET VOUT = (VSD + VOFFSET) (1 + R/R1)/2 TYPICAL: R = 50k C = 0.01F f-3dB = 1/(2RC) = 318Hz 03277- 0- 018 Figure 33. Sigma-Delta Active Filter with Gain and Offset Input Signal Voltage VAIN +1.0 V VAIN = +1.0 V - (1 LSB) VAIN = +1.0 V - (2 LSB) ... VAIN = 0 V + 1 LSB VAIN = 0.0 V VAIN = 0 V - 1 LSB ... VAIN = -1.0 V + (2 LSB) VAIN = -1.0 V VAIN < -1.0 V DRIVING THE INPUT RECEIVE PATH (Rx) The AD9878 includes three high speed, high performance ADCs. The 10-bit and dual 12-bit direct IF ADCs deliver excellent undersampling performance with input frequencies as high as 70 MHz. The sampling rate can be as high as 33 MSPS. The ADC sampling frequency can be derived directly from the OSCIN signal or from the on-chip OSCIN multiplier. For highest dynamic performance, it is recommended to choose an OSCIN frequency that can be directly used as the ADC sampling clock. Digital 12-bit ADC outputs are multiplexed to one 12-bit bus, clocked by a frequency (fMCLK) of four times the sampling rate. The IF ADCs use a multiplexer to a 12-bit interface with an output word rate of fMCLK. IF10 AND IF12 ADC OPERATION The IF10 and IF12 ADCs have a common architecture and share many of the same characteristics from an applications standpoint. Most of the information in the section below will be applicable to both IF ADCs. Differences, where they exist, will be highlighted. The IF ADCs have differential switched capacitor sample-andhold amplifier (SHA) inputs. The nominal differential input impedance is 4.0 k||3 pF. This impedance can be used as the effective termination impedance when calculating filter transfer characteristics and voltage signal attenuation from nonzero source impedances. It should be noted, however, that for best performance, additional requirements must be met by the signal source. The SHA has input capacitors that must be recharged each time the input is sampled. This results in a dynamic input current at the device input, and demands that the source has low (<50 ) output impedance at frequencies up to the ADC sampling frequency. Also, the source must have settling to better than 0.1% in <1/2 ADC CLK period. Another consideration for getting the best performance from the ADC inputs is the dc biasing of the input signal. Ideally, the signal should be biased to a dc level equal to the midpoint of the ADC reference voltages, REFT12 and REFB12. Nominally, this level will be 1.2 V. When ac-coupled, the ADC inputs will selfbias to this voltage and require no additional input circuitry. Figure 34 illustrates a recommended circuit that eases the burden on the signal source by isolating its output from the ADC input. The 33 series termination resistors isolate the amplifier outputs from any capacitive load, which typically improves settling time. The series capacitors provide ac signal coupling which ensures that the ADC inputs operate at the Rev. 0 | Page 24 of 36 AD9878 optimal dc bias voltage. The shunt capacitor sources the dynamic currents required to charge the SHA input capacitors, removing this requirement from the ADC buffer. The values of CC and CS should be calculated to get the correct HPF and LPF corner frequencies. 33 CC 33 CC VS AINP of the reference pins REFT and REFB. External references may be necessary for systems that require high accuracy gain matching between ADCs or for improvements in temperature drift and noise characteristics. External references REFT and REFB need to be centered at AVDD/2 with offset voltages as specified: REFT-10, -12: AVDD/2 + 0.5 V REFB-10, -12: AVDD/2 - 0.5 V CS AINN A differential level of 1 V between the reference pins results in a 2 V p-p ADC input level AIN. Internal reference sources can be powered down when external references are used (Register Address 0x02). 03277- 0- 019 Figure 34. Simple ADC Drive Configuration RECEIVE TIMING The AD9878 sends multiplexed data to the IF10 and IF12 outputs on every rising edge of MCLK. RxSYNC frames the start of each IF10 data symbol. 10-bit and 12-bit ADCs are completely read on every second MCLK cycle. RxSYNC is high for every second 10-bit ADC data (if 10-bit ADC is not in power-down mode).The Rx timing diagram is shown in Figure 35. tEE OSCOUT M/N = 2 tMD tOD MCLK IF10 DATA IF10[9:5] IF10[4:0] IF10[9:5] IF10[4:0] IF10[9:5] IF10[4:0] VIDEO INPUT For sampling video-type waveforms, such as NTSC and PAL signals, the Video Input channel provides black level clamping. Figure 36 shows the circuit configuration for using the Video Channel input (Pin 98). An external blocking capacitor is used with the on-chip video clamp circuit to level-shift the input signal to a desired reference point. The clamp circuit automatically senses the most negative portion of the input signal, and adjusts the voltage across the input capacitor. This forces the black level of the input signal to be equal to the value programmed into the Clamp Level register (Register Address 0x07).Video Input can be multiplexed to the IF12A ADC (default) or to the IF12B ADC by programming Register Address 0x03. RxSYNC CLAMP LEVEL +FS/2 IF12 DATA IF12A IF12B IF12B IF12B IF12A AD9878 IF12B Rx PORT TIMING (DEFAULT MODE: MUXED IF12 ADC DATA) 2mA CLAMP LEVEL M/N = 2 tMD tOD + DAC LPF OFFSET Figure 36. Video Clamp Circuit Input IF10[9:5] IF10[4:0] IF10[9:5] IF10[4:0] IF10[9:5] IF10[4:0] IF12A OR IF12B IF12A OR IF12B PCB DESIGN CONSIDERATIONS Although the AD9878 is a mixed-signal device, the part should be treated as an analog component. The digital circuitry onchip has been specially designed to minimize the impact that the digital switching noise will have on the operation of the analog circuits. Following the power, grounding, and layout recommendations in this section will help the user get the best performance from the MxFE. RxSYNC IF DATA - 03277- 0- 021 MCLK IF10 DATA VIDEO INPUT 0.1F BUFER ADC tEE OSCOUT CLAMP LEVEL 12 IF12A OR IF12B Rx PORT TIMING (OUTPUT DATA FROM ONLY ONE IF12 ADC) 03277- 0- 020 Figure 35. Rx Port Timing ADC VOLTAGE REFERENCES The AD9878 has three independent internal references for its 10-bit and 12-bit ADCs. Both 12-bit and 10-bit ADCs are designed for 2 V p-p input voltages with each of them having its own internal reference. Figure 28 shows the proper connections COMPONENT PLACEMENT If the three following guidelines of component placement are followed, chances for getting the best performance from the MxFE are greatly increased. Rev. 0 | Page 25 of 36 AD9878 * First, manage the path of return currents flowing in the ground plane so that high frequency switching currents from the digital circuits do not flow on the ground plane under the MxFE or analog circuits. * Second, keep noisy digital signal paths and sensitive receive signal paths as short as possible. * Third, keep digital (noise generating) and analog (noise susceptible) circuits as far away from each other as possible. In order to best manage the return currents, pure digital circuits that generate high switching currents should be closest to the power supply entry. This will keep the highest frequency return current paths short, and prevent them from traveling over the sensitive MxFE and analog portions of the ground plane. Also, these circuits should be generously bypassed at each device to further reduce the high frequency ground currents. The MxFE should be placed adjacent to the digital circuits, such that the ground return currents from the digital sections will not flow in the ground plane under the MxFE. The analog circuits should be placed furthest from the power supply. The AD9878 has several pins that are used to decouple sensitive internal nodes. These pins are REFIO, REFB12A, REFT12A, REFB12B, REFT12B, REFB10, and REFT10. The decoupling capacitors connected to these points should have low ESR and ESL. The capacitors should be placed as close to the MxFE as possible and be connected directly to the analog ground plane. The resistor connected to the FSADJ pin and the RC network connected to the PLLFILT pin should also be placed close to the device and connected directly to the analog ground plane. POWER PLANES AND DECOUPLING The AD9878 evaluation board (Figure 38 and Figure 39) demonstrates a good power supply distribution and decoupling strategy. The board has four layers: two signal layers, one ground plane, and one power plane. The power plane is split into a 3 VDD section that is used for the 3 V digital logic circuits, a DVDD section that is used to supply the digital supply pins of the AD9878, an AVDD section that is used to supply the analog supply pins of the AD9878, and a VANLG section that supplies the higher voltage analog components on the board. The 3 VDD section will typically have the highest frequency currents on the power plane and should be kept the furthest from the MxFE and analog sections of the board. The DVDD portion of the plane carries the current used to power the digital portion of the MxFE to the device. This should be treated similarly to the 3 VDD power plane and be kept from going underneath the MxFE or analog components. The MxFE should largely sit above the AVDD portion of the power plane. The AVDD and DVDD power planes may be fed from the same low noise voltage source; however, they should be decoupled from each other to prevent the noise generated in the DVDD portion of the MxFE from corrupting the AVDD supply. This can be done by using ferrite beads between the voltage source and DVDD, and between the source and AVDD. Both DVDD and AVDD should have a low ESR, bulk decoupling capacitor on the MxFE side of the ferrite as well as low ESR, ESL decoupling capacitors on each supply pin (i.e., the AD9878 requires 17 power supply decoupling capacitors). The decoupling capacitors should be placed as close to the MxFE supply pins as possible. An example of proper decoupling is shown in the AD9878 evaluation board schematic (Figure 38 and Figure 39). GROUND PLANES In general, if the component placing guidelines discussed earlier can be implemented, it is best to have at least one continuous ground plane for the entire board. All ground connections should be made as short as possible. This will result in the lowest impedance return paths and the quietest ground connections. If the components cannot be placed in a manner that would keep the high frequency ground currents from traversing under the MxFE and analog components, it may be necessary to put current steering channels into the ground plane to route the high frequency currents around these sensitive areas. These current steering channels should be made only when and where necessary. SIGNAL ROUTING The digital Rx and Tx signal paths should be kept as short as possible. Also, these traces should have a controlled impedance of about 50 . This will prevent poor signal integrity and the high currents that can occur during undershoot or overshoot caused by ringing. If the signal traces cannot be kept shorter than about 1.5 inches, then series termination resistors (33 to 47 ) should be placed close to all signal sources. It is a good idea to series terminate all clock signals at their source regardless of trace length. The receive signals are the most sensitive signals on the entire board. Careful routing of these signals is essential for good receive path performance. The IF+/IF- signals form a differential pair and should be routed together as a pair. By keeping the traces adjacent to each other, noise coupled onto the signals will appear as common mode and will be largely rejected by the MxFE receive input. Keeping the driving point impedance of the receive signal low and placing any low-pass filtering of the signals close to the MxFE will further reduce the possibility of noise corrupting these signals. Rev. 0 | Page 26 of 36 AD9878 AVDD AGND VIDEO IN AGND IF12A+ IF12A- AGND AVDD REFT12A REFB12A AVDD AGND IF12B+ IF12B- AGND AVDD REFT12B REFB12B AVDD AGND AVDD10 AGND10 IF10+ IF10- AGND PIN CONFIGURATION AND PIN FUNCTION DESCRIPTIOINS 100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76 DRGND 1 75 REFT10 DRVDD 2 74 REFB10 IF12(11) 3 73 AGND10 IF12(10) 4 72 AVDD10 IF12(9) 5 71 DRVDD IF12(8) 6 70 DRGND IF12(7) 7 69 REFCLK IF12(6) 8 68 SIGDELT IF12(5) 9 67 FLAD(0) IF12(4) 10 66 FLAG(1) IF12(3) 11 65 CA_EN 64 CA_DATA 63 CA_CLK 62 DVDDOSC 61 OSCIN IF10(3) 16 60 XTAL IF10(2) 17 59 DGNDOSC IF10(1) 18 58 AGNDPLL IF10(0) 19 57 PLLFILT RxSYNC 20 56 AVDDPLL DRGND 21 55 DVDDPLL DRVDD 22 54 DGNDPLL MCLK 23 53 AVDDTx DVDD 24 52 Tx+ DGND 25 51 Tx- AD9878 100-LEAD LQFP IF12(2) 12 IF12(1) 13 TOP VIEW (Not to Scale) IF12(0) 14 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 TxSYNC TxIQ(5) TxIQ(4) TxIQ(3) TxIQ(2) TxIQ(1) TxIQ(0) DVDD DGND DVDD DGND PROFILE RESET DVDD DGND SCLK CS SDIO SDO DGNDTx DVDDTx PWRDN REFIO FSADJ AGNDTx IF10(4) 15 03277- 0- 002 Figure 37. Pin Configuration Table 7. Pin Function Descriptions Pin No. 1, 21, 70 2, 22, 71 3-14 15-19 20 23 24, 35, 39 25, 34, 36, 40 26 27:32 37 38 41 42 43 44 45 46 47 48 49 Mnemonic DRGND DRVDD IF12[11:0] IF10[4:0] RxSYNC MCLK DVDD DGND TxSYNC TxIQ[5:0] PROFILE RESET SCLK CS SDIO SDO DGNDTx DVDDTx PWRDN REFIO FSADJ Pin Function Pin Driver Digital Ground Pin Driver Digital 3.3 V Supply 12-Bit ADCs Digital Ouput 10-Bit ADC Digital Ouput Sync Output, 10- and 12-Bit ADCs Master Clock Output Digital 3.3 V Supply Digital Ground Sync Input for Transmit Port Digital Input for Transmit Port Profile Selection Input Chip Reset Input SPORT Clock SPORT Chip Select SPORT Data I/O SPORT Data Output Tx Path Digital Ground Tx Path Digital 3.3 V Supply Power-Down Transmit Path TxDAC Decoupling (to AGND) DAC Output Adjust (External Res.) Rev. 0 | Page 27 of 36 AD9878 Pin No. 50 51, 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66, 67 68 69 72, 80 73, 79 74 75 76, 81, 86, 89, 94, 97, 99 77, 78 82, 85, 90, 93, 100 83 84 87, 88 91 92 95, 96 98 Mnemonic AGNDTx Tx-, Tx+ AVDDTx DGNDPLL DVDDPLL AVDDPLL PLLFILT AGNDPLL DGNDOSC XTAL OSCIN DVDDOSC CA_CLK CA_DATA CA_EN FLAG[2:1] SIGDELT REFCLK AVDD10 AGND10 REFB10 REFT10 AGND IF10-, IF10+ AVDD REFB12B REFT12B IF12B-, IF12B+ REFB12A REFT12A IF12A-, IF12A+ VIDEO IN Pin Function Tx Path Analog Ground Tx Path Complementary Outputs Tx Path Analog 3.3 V Supply PLL Digital Ground PLL Digital 3.3 V Supply PLL Analog 3.3 V Supply PLL Loop Filter Connection PLL Analog Ground Oscillator Digital Ground Crystal Oscillator Inverted Output Oscillator Clock Input Oscillator Digital 3.3 V Supply Serial Clock to Cable Driver Serial Data to Cable Driver Serial Enable to Cable Driver Programmable Flag Outputs Sigma-Delta DAC Output Reference Clock Output 10-Bit ADC Analog 3.3 V Supply 10-Bit ADC Analog Ground 10-Bit ADC Ref Decoupling Node 10-Bit ADC Ref Decoupling Node 12-Bit ADC Analog Ground Differential Input to 10-bit ADC 12-Bit ADC Analog 3.3 V Supply ADC12B Ref Decoupling Node ADC12B Ref Decoupling Node Differential Input to ADC12B ADC12A Ref Decoupling Node ADC12A Ref Decoupling Node Differential Input to ADC12A Video Clamp Input Rev. 0 | Page 28 of 36 Rev. 0 | Page 29 of 36 Figure 38. AD9878 Evaluation PCB Schematic (page1) J12 R24 49.9 2 1 RC0805 R23 523 499 RC0805 C96 16V 10UF A_BUFF- 1 8 4 RC0805 BCASE 3 VCC U9 -IN CC0805 C90 3 2 1 499 499 R17 0.1UF CC0805 C97 R22 VOVOC VO+ 2 0.1UF 0.1UF T3 DIP06RCUP 4 5 6 RC0805 RC0805 C102 33 47PF CC1206 C88 R21 33 R25 VCML J11 C110 49.9 R20 3 2 1 T2 DIP06RCUP 2 0.1UF 4 5 6 RC0805 WHT C86 RC0805 C94 RC0805 JP22 33 R19 33 R13 SDELTA0 REFCLK FLAG2 FLAG1 CAENABLE CADATA R3 0.1UF IF12A- 20PF J4 0.1UF CC0603 C3 0.1UF CC0603 C7 2 SMAEDGE 1 AGND;3,4,5 VIDEO IN J1 0.1UF CC0603 C2 0.1UF CC0603 C6 0.1UF CC0603 C13 BCASE 0.1UF CC0603 C5 0.1UF C9 CC0603 R2 C12 RC0805 3 RC0805 RC0805 37.5 37.5 R12 R11 0.1UF CC0805 C72 AVDD DRVDD XTAL OSCIN 100 99 97 98 96 93 94 95 92 90 91 88 89 87 86 84 85 83 81 82 78 79 80 77 75 76 74 71 72 73 70 68 69 66 67 65 62 63 64 61 59 60 56 57 58 55 53 54 52 51 TX+ AGND7 AVDD5 AGND6 VIDEOIN IF12A+ AVDD4 AGND5 IF12A- REFT12A AVDD3 REFB12A IF12B+ AGND4 IF12B- AGND3 REFT12B AVDD2 REFB12B AVDD10-A AGND2 AVDD1 AGND10-A IF10BIF10B+ REFT10 AGND1 REFB10 AGND10 DRVDD AVDD10 DRGND SIGDELT REFCLK FLAG2 FLAG1 CAEN CADATA DVDDOSC CACLK OSCIN DGNDOSC XTAL PLLFILT AGNDPLL DVDDPLL AVDDPLL 50 45 SDO 44 SDIO 43 CS 42 SCLK 41 DGND4 40 DVDD4 39 RESET 38 PROFILE 37 DGND3 36 DVDD3 35 DGND2 34 DVDD2 33 TXIQ0 32 TXIQ1 31 TXIQ2 30 TXIQ3 29 TXIQ4 28 TXIQ5 27 TXSYNC 26 DGND1 25 DVDD1 24 MCLK 23 DRVDD2 22 DRGND2 21 RXSYNC 20 IFB0 19 IFB1 18 IFB2 17 IFB3 16 IFB4 15 IF0 14 IF1 13 IF2 12 IF3 11 IF4 10 IF5 9 IF6 8 IF7 7 IF8 6 IF9 5 IF10 4 IF11 3 DRVDD1 2 DRGND1 1 49 REFIO 48 PWRDN 47 DVDDTX 46 DGNDTX FSADJ TXAVDDTX DGNDPLL RC0805 2 A B 3 AD8328 JP7 TX- TRANSF1 12 SLEEP 11 GND4 7 8 5 6 3 4 1 2 IF11 IF9 IF10 IF8 IF6 IF7 IF4 IF5 IF2 IF3 IF0 IF1 C21 DVDDTX C22 0.1UF IFB4 IFB1 IFB2 IFB3 IFB0 RXSYNC MCLK TXSYNC TXIQ5 TXIQ4 TXIQ2 TXIQ3 TXIQ1 PROFILE1 TXIQ0 DVDD SCLK SDIO CS SDO LC1210 220 L14 C57 CC0603 LC1210 L15 220 CACLK 18PF 1 2 75 R36 75 R38 RC0805 59 R37 AGND;5 RESET 3 4 RC0805 SW1 RESET C58 CC0805 CAENABLE CADATA 33PF CC0805 PWRDOWN 0.1UF CC0603 DRVDD R10 10K LC1210 L13 C20 220 18PF CC0805 LC1210 L16 220 SDATA 9 CLK 10 16 VOUT+ U4 VIN+ 15 VOUTVIN14 BYP GND3 13 NC DATAEN 20 GND5AD8328 GND 19 VCC1 VCC 18 TXEN GND1 17 RAMP GND2 2 A B 3 AD8328 JP8 TX+ TRANSF1 CA_SLEEP C116 0.1UF 0.1UF 0.1UF RC0805 U2 AD9878LQFP AGNDTX AVDDTX DVDDPLLOSC C24 0.1UF 0.1UF CC0603 WHT TP2 RC0805 T6 2 P 1 5 S TOKOB5F 4 0.1UF 1.3K 33OHM R1 75OHM 10UF 10V C4 BCASE 10UF C8 10V 10UF BCASE 16V C14 WHT TP1 R4 4 3 T1 5 6 C23 RC0805 2 1 43.3 R39 DIP06RCUP 86.6 R40 WHT TP5 1 C16 2 SMAEDGE WHT TP6 CC0603 C11 WHT 0.1UF CC0805 C92 VCML IF12A+ IF12B+ IF12B- IF10+ IF10- WHT TP3 1 AGND;3,4,5 TRANSF TX_OUT 2 SMAEDGE AGND;3,4,5 J8 0.01UF TP15 CC0603 C66 100K 0.1UF C69CC0603 CACLK TP4 0.01UF C15 0.1UF 8138+ VCML JP23 TRANSF A B 3 XTAL CC0603 JP21 AD8138 2 TRANSF 3 B A 1 OSCIN EXT_CLK JP1 Y1 VAL AD81381 RC0805 IF-12A 1 8138- 2 SMAEDGE 5.11K R16 IF12B- 20PF C98 IF12B+ IF10- CC0805 20PF 2 1 33 IF10+ CC0805 C108 VCML 3 C84 CC0805 16V CC0805 10UF 0.1UF 0.1UF C83 R5 C17 RC0805 AGND;3,4,5 CC0805 0.1UF RC0805 C95 47PF CC1206 33 R14 10K R15 JP4 0.1UF C87 JP24 TRANSF 33 R26 C101 RC0805 33 R32 33 C112 RC0805 TRANSF JP30 JP26 1 A B 3 AD8138 2 TRANSF 0.1UF AD8138 5 RC0805 +IN VEE 6 BCASE 8138- R27 4 5 JP32 A B 3 2 T5 6 AD8138 2 3 B A 1 JP25 AD81381 3 2 1 DIP06RCUP 4 18PF C18 R31 18PF RC0805 U13 NC7SZ04 2 AGND;3 V_CLK;5 C111 AD8138 2 TRANSF 3 B A 1 JP31 0.1UF RC0805 RC0805 R18 C91 10UF 16V RC0805 2 49.9 1 8138+ 8138- R33 8138+ 500 R7 CC0603 A_BUFF+ J13 SMAEDGE AGND;3,4,5 RC0805 2 49.9 1 IF-12B J15 SMAEDGE 0.1UF C19 10K BCASE RC0805 SMAEDGE AGND;3,4,5 AD8138 R9 49.9 IF-10 SMA200UP AGND;3,4,5 AGND;3,4,5 J3 OSC_IN_CLK 500 CC0603 C117 C115 CC0603 CC0603 CC0603 TX_OUT AD8328 RC0805 POT1 V_CLK R2 RC0805 R3 3 R6 R5 5V_AD8328 R4 4 5 DUTY CYCLE CC0603 RC07CUP R6 CC0603 1 U1 VCC GND 3 2 JP9 R29 10K 3 1 5 9 7 15 13 11 17 21 19 23 25 4 2 6 10 8 16 14 12 18 22 20 24 26 03277-0-038 IF[0:11] IFB[0:4] RIBBON J2 SDO,SDIO,CS,SCLK DRVDD C1 0.1UF DRVDD PWRDOWN ADM1818-10ART RESET C113 0.01UF C114 0.01UF R8 R28 1K 1 RCOM R1 2 22 RC0805 R7 CC0603 R9 RC0805 6 7 8 CC0603 0.1UF CC0603 RP1 RC0805 9 CW CC0603 RC0805 CC0805 10 CC0603 CC0603 CC0805 CC0805 CC0603 HEADER RA RIBBON CC0603 DIGITAL TRANSMIT 5V_AD8328 AD9878 C10 CC0603 8 7 6 5 4 3 2 5V 3_3VD ABUFF+ JP2 1 ABUFF- 3_3VA AD8328 C28 C29 C43 C30 C45 0.1UF 0.1UF CC0603 CC0603 CC0603 C46 DBUFF3-5V C47 C50 C55 C53 C100 CC0603 CC0603 CC0603 CC0603 0.1UF 0.1UF 0.1UF 0.1UF 0.1UF DBUFF5V DBUFF3-5V C39 0.1UF C56 C54 C51 C48 CC0603 CC0603 CC0603 0.1UF 0.1UF 0.1UF 0.1UF C36 C33 CC0603 0.1UF 0.1UF CC0603 DBUFF5V 22 IFB[0:4] IF[0:11] 7 C44 CC0603 C49 0.1UF DVDDTX CC0603 C37 0.1UF DRVDD CC0603 HDR040RA 38 40 36 37 39 34 35 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 8 TP11 CLR C34 0.1UF RIBBON 33 31 29 27 25 23 21 19 17 15 13 11 9 7 5 3 1 J5 5 6 CC0805 TP10 CLR TP9 CLR CC0603 0.1UF C32 C35 C38 CC0603 CC0603 0.1UF 0.1UF 0.1UF C31 0.1UF C75 CC0603 DVDD 0.1UF DVDDPLLOSC CC0603 C52 CC0603 CC0603 C73 CC0603 5V_AD8328 0.1UF TP8 CLR TP7 CLR TP19 CLR 0.1UF CC0805 VAL 0.1UF CC0805 VAL 0.1UF CC0805 VAL 0.1UF CC0805 VAL 0.1UF CC0805 VAL 0.1UF TP13 CLR A_BUFF+ A_BUFF- AVDDPLL 0.1UF C65 0.1UF CC0603 3 4 BCASE C82 CC0805 VAL 0.1UF TP12 CLR C70 CC0603 0.1UF C68 AVDD CC0603 IF0 6 C41 10UF 16V C80 CC0805 VAL 0.1UF TP14 CLR TP16 CLR 0.1UF AVDDTX C71 0.1UF CC0603 RP6 VAL C81 CC0805 VAL 0.1UF C67 CC0603 C74 0.1UF CC0603 22 2 LC1210 C63 CC0805 VAL 0.1UF C76 0.1UF CC0603 RP6 7 8 L5 LC1210 C64 CC0805 VAL TP17 CLR C85 0.1UF CC0603 22 C42 10UF 16V LC1210 LC1210 LC1210 LC1210 LC1210 LC1210 LC1210 LC1210 LC1210 0.1UF CC0805 RP6 L6 C27 10UF 16V L3 C40 10UF 16V L4 C26 10UF 16V L2 C25 10UF 16V L1 C79 10UF 16V L12 C77 10UF 16V L10 16V 10UF C78 L11 C60 10UF 16V L8 C61 10UF 16V L9 C59 10UF 16V RP6 22 1 2 A B 3 JP13 5 BCASE BCASE BCASE BCASE BCASE BCASE BCASE BCASE BCASE BCASE BCASE TP18 CLR DIGITAL RECEIVE C62 23 VAL RP6 22 IF10 LC1210 15 22 IF9 RP6 IF8 L7 19 RP6 22 IF7 V_CLK 20 J7 IFB4 2 SMAEDGE 1 MCLK AGND;3,4,5 33 U7 NC7SZ04 2 4 U3 RC0603 AGND;3 DBUFF5V;5 R35 16 RP4 22 DVDD CA_SLEEP INVERT CLK 0.1UF 24 RP6 22 IF6 14 CC0805 21 RP4 22 DEL_CLK BCASE 22 22 IF5 DEL_CLK R8 R34 U8 RC0603 100 RC0603 1K 24 TP20 CLR 16 RP5 IF4 JP3 SSDIO SCS SDOPC SSCLK 16 C93 17 22 IF2 15 VAL 18 RP5 IF1 14 LC1210 19 22 4 IFB3 24 1 20 RP5 IFB2 VCCB 16 U5 14 NC 9 RP5 22 3 IFB1 VCCA 2 T/R 10 OE A7 IF11 B7 A6 9 B6 17 B5 13 GND3 18 B4 74LVXC3245 A3 6 B3 A2 5 B2 A1 4 B1 A0 3 B0 GND1 11 TSSOP24 GND2 12 23 VCCB VCCA 1 14 NC T/R 2 OE 21 B1 15 B7 A6 9 B6 U6 A5 8 B5 74LVXC3245 A4 7 B4 A3 6 B3 A2 5 B2 A1 4 A7 10 IF3 A5 8 10 RP5 22 2 IFB0 GND3 13 B0 A0 3 GND1 11 24 1 13 C89 10UF 16V 2 TSSOP24 GND2 12 23 VCCB 1 7 VCCA 22 OE NC T/R 21 B0 A1 4 A0 3 8 1 JP5 A B 2 13 RP4 22 4 15 2 20 RP4 22 3 19 B1 18 B2 6 5 9 B3 74LVXC3245 A3 7 A2 5 6 11 A4 8 DEL_CLK A4 7 11 22 12 22 13 RP7 14 RP7 15 22 16 22 2 9 RP5 RP7 10 RP5 22 1 11 RP5 22 MCLK 12 22 RXSYNC 13 22 16 RP7 14 3 15 4 12 RP4 22 5 17 10 RP4 22 7 RP4 22 8 RP4 22 6 16 B4 A5 15 B5 A6 14 B6 9 GND3 13 B7 A7 10 GND1 11 TSSOP24 GND2 12 23 VCCB VCCA 1 21 22 NC 2 T/R 20 OE 3 A0 SDOPC 18 B2 19 B0 A1 4 B1 A2 5 Figure 39. AD9878 Evaluation PCB Schematic (page2) A3 8 6 7 CS 6 SDIO 22 RP3 5 74LVXC3245 22 RP3 4 7 Rev. 0 | Page 30 of 36 22 RP3 3 17 B3 9 22 RP3 2 B4 10 22 RP3 1 A4 11 22 RP3 8 A5 12 22 RP3 7 8 13 22 RP3 6 SCLK 14 22 RP2 5 B5 15 22 RP2 4 A6 16 22 RP2 3 9 9 22 RP2 2 B6 10 22 RP2 1 B7 11 22 RP2 10 12 22 RP2 J6 8 7 6 5 4 3 2 1 P1 9 10 SDO 12 PC PARALLEL PORT 03277-0-039 25 24 23 22 21 20 19 18 17 16 15 14 11 RJ45 DCN25RPT 13 12 11 10 9 8 7 6 5 4 3 2 1 GND3 13 22 RP2 TSSOP24 14 A7 15 GND1 16 GND2 3 JP6 3 A B 2 11 1 12 L17 AD9878 1 1 AD9878 03277-0-040 Figure 40. AD9878 Evaluation PCB--Top Assembly 03277-0-041 Figure 41. AD9878 Evaluation PCB--Bottom Assembly Rev. 0 | Page 31 of 36 AD9878 03277-0-042 Figure 42. AD9878 Evaluation PCB Layout--Top Layer 03277-0-043 Figure 43. AD9878 Evaluation PCB Layout--Bottom Layer Rev. 0 | Page 32 of 36 AD9878 03277-0-044 Figure 44. AD9878 Evaluation PCB--Power Plane Figure 45. AD9878 Evaluation PCB--Ground Plane Rev. 0 | Page 33 of 36 AD9878 OUTLINE DIMENSIONS 1 6 .0 0 BSC SQ 1 .6 0 MAX 0 .7 5 0 .6 0 0 .4 5 1 4 .0 0 BSC SQ 12 TYP 100 1 76 75 PIN 1 SEATING PLANE 1 2 .0 0 REF TOP VIEW 1 .4 5 1 .4 0 1 .3 5 0 .1 5 0 .0 5 10 6 2 SEATING PLANE ( PINS DOWN) 0 .20 0 .09 7 3 .5 0 0 .0 8 MAX COPLANARITY VIEW A 25 51 50 26 0 .5 0 BSC VIEW A 0 .27 0 .22 0 .17 ROTATED 9 0 CCW COMPLIANT TO JEDEC STANDARDS MS-0 2 6 BED Figure 46. 100-Lead Low Profile Quad FlapPackage [LQFP] (ST-100) Dimensions shown in millimeters ESD CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. ORDERING GUIDE Model AD9878BST AD9878BSTRL Temperature Range -40C to +85C Package Description 100-LQFP Package Option ST-100 -40C to +85C 100-LQFP ST-100 Rev. 0 | Page 34 of 36 AD9878 NOTES Rev. 0 | Page 35 of 36 AD9878 NOTES (c) 2003 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective companies. C03277-0-5/03(0) Rev. 0 | Page 36 of 36