8-Bit, 125 MSPS, Dual TxDAC+ Digital-to-Analog Converter AD9709
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8-Bit, 125 MSPS, Dual TxDAC+ Digital-to-Analog Converter AD9709
8-Bit, 125 MSPS, Dual TxDAC+ Digital-to-Analog Converter AD9709 FUNCTIONAL BLOCK DIAGRAM 8-bit dual transmit digital-to-analog converter (DAC) 125 MSPS update rate Excellent SFDR to Nyquist @ 5 MHz output: 66 dBc Excellent gain and offset matching: 0.1% Fully independent or single-resistor gain control Dual port or interleaved data On-chip 1.2 V reference Single 5 V or 3.3 V supply operation Power dissipation: 380 mW @ 5 V Power-down mode: 50 mW @ 5 V 48-lead LQFP DVDD1/ DCOM1/ DVDD2 DCOM2 AVDD 1 LATCH PORT1 WRT1/IQWRT WRT2/IQSEL ACOM DIGITAL INTERFACE MODE APPLICATIONS 1 DAC IOUTA1 IOUTB1 REFERENCE REFIO FSADJ1 FSADJ2 GAINCTRL BIAS GENERATOR SLEEP AD9709 2 LATCH PORT2 CLK1 2 DAC IOUTA2 IOUTB2 CLK2/IQ RESET 00606-001 FEATURES Figure 1. Communications Base stations Digital synthesis Quadrature modulation 3D ultrasound GENERAL DESCRIPTION 1 www.BDTIC.com/ADI The AD9709 is a dual-port, high speed, 2-channel, 8-bit CMOS DAC. It integrates two high quality 8-bit TxDAC+® cores, a voltage reference, and digital interface circuitry into a small 48-lead LQFP package. The AD9709 offers exceptional ac and dc performance while supporting update rates of up to 125 MSPS. The AD9709 has been optimized for processing I and Q data in communications applications. The digital interface consists of two double-buffered latches as well as control logic. Separate write inputs allow data to be written to the two DAC ports independent of one another. Separate clocks control the update rate of the DACs. A mode control pin allows the AD9709 to interface to two separate data ports, or to a single interleaved high speed data port. In interleaving mode, the input data stream is demuxed into its original I and Q data and then latched. The I and Q data is then converted by the two DACs and updated at half the input data rate. The GAINCTRL pin allows two modes for setting the full-scale current (IOUTFS) of the two DACs. IOUTFS for each DAC can be set independently using two external resistors, or IOUTFS for both DACs can be set by using a single external resistor. See the Gain Control Mode section for important date code information on this feature. The DACs utilize a segmented current source architecture combined with a proprietary switching technique to reduce 1 glitch energy and to maximize dynamic accuracy. Each DAC provides differential current output, thus supporting singleended or differential applications. Both DACs can be simultaneously updated and provide a nominal full-scale current of 20 mA. The full-scale currents between each DAC are matched to within 0.1%. The AD9709 is manufactured on an advanced low-cost CMOS process. It operates from a single supply of 3.3 V or 5 V and consumes 380 mW of power. PRODUCT HIGHLIGHTS 1. 2. 3. 4. 5. 6. The AD9709 is a member of a pin-compatible family of dual TxDACs providing 8-, 10-, 12-, and 14-bit resolution. Dual 8-Bit, 125 MSPS DACs. A pair of high performance DACs optimized for low distortion performance provide for flexible transmission of I and Q information. Matching. Gain matching is typically 0.1% of full scale, and offset error is better than 0.02%. Low Power. Complete CMOS dual DAC function operates at 380 mW from a 3.3 V or 5 V single supply. The DAC full-scale current can be reduced for lower power operation, and a sleep mode is provided for low power idle periods. On-Chip Voltage Reference. The AD9709 includes a 1.20 V temperature-compensated band gap voltage reference. Dual 8-Bit Inputs. The AD9709 features a flexible dualport interface, allowing dual or interleaved input data. Patent pending. Rev. A 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 owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2000–2008 Analog Devices, Inc. All rights reserved. AD9709 TABLE OF CONTENTS Features .............................................................................................. 1 Analog Outputs .......................................................................... 14 Applications....................................................................................... 1 Digital Inputs .............................................................................. 15 Functional Block Diagram .............................................................. 1 DAC Timing................................................................................ 15 General Description ......................................................................... 1 Sleep Mode Operation............................................................... 18 Product Highlights ........................................................................... 1 Power Dissipation....................................................................... 18 Revision History ............................................................................... 2 Applying the AD9709 .................................................................... 19 Specifications..................................................................................... 3 Output Configurations .............................................................. 19 DC Specifications ......................................................................... 3 Differential Coupling Using a Transformer............................ 19 Dynamic Specifications ............................................................... 4 Differential Coupling Using an Op Amp................................ 19 Digital Specifications ................................................................... 5 Single-Ended, Unbuffered Voltage Output............................. 20 Absolute Maximum Ratings............................................................ 6 Single-Ended, Buffered Voltage Output Configuration........ 20 Thermal Resistance ...................................................................... 6 Power and Grounding Considerations.................................... 20 ESD Caution.................................................................................. 6 Applications..................................................................................... 22 Pin Configuration and Function Descriptions............................. 7 Typical Performance Characteristics ............................................. 8 Quadrature Amplitude Modulation (QAM) Using the AD9709 ...................................................................... 22 Terminology .................................................................................... 11 CDMA ......................................................................................... 23 Theory of Operation ...................................................................... 12 Evaluation Board ............................................................................ 24 Functional Description.............................................................. 12 General Description................................................................... 24 Reference Operation .................................................................. 13 Schematics................................................................................... 24 Gain Control Mode .................................................................... 13 Evaluation Board Layout........................................................... 27 Setting the Full-Scale Current................................................... 13 Outline Dimensions ....................................................................... 30 DAC Transfer Function ............................................................. 14 Ordering Guide............................................................................... 30 www.BDTIC.com/ADI REVISION HISTORY 1/08—Rev. 0 to Rev. A Updated Format..................................................................Universal Changed Single Supply Operation to 5 V or 3.3 V ........Universal Changes to Figure 1.......................................................................... 1 Added Timing Diagram Section .................................................... 5 Changes to Figure 3 and Table 6..................................................... 7 Change to Figure 12 ......................................................................... 9 Changes to Figure 18 to Figure 20................................................ 10 Changes to Functional Description Section ............................... 13 Changes to Reference Operation Section.................................... 13 Changes to Figure 23 and Figure 24............................................. 13 Changes to Gain Control Mode Section...................................... 13 Replaced Reference Control Amplifier Section with Setting the Full-Scale Current Section................................................. 13 Changes to DAC Transfer Function Section............................... 14 Changes to Interleaved Mode Timing Section ........................... 16 Added Figure 28 ............................................................................. 16 Changes to Power and Grounding Considerations Section ..... 20 Changes to Figure 44...................................................................... 22 Deleted Figure 43............................................................................ 17 Changes to CDMA Section ........................................................... 23 Changes to Figure 45 Caption ...................................................... 23 Changes to Figure 46...................................................................... 24 Changes to Figure 48...................................................................... 26 Updated Outline Dimensions....................................................... 30 Changes to Ordering Guide .......................................................... 30 5/00—Revision 0: Initial Version Rev. A | Page 2 of 32 AD9709 SPECIFICATIONS DC SPECIFICATIONS TMIN to TMAX, AVDD = 3.3 V or 5 V, DVDD1 = DVDD2 = 3.3 V or 5 V, IOUTFS = 20 mA, unless otherwise noted. Table 1. Parameter RESOLUTION DC ACCURACY 1 Integral Linearity Error (INL) Differential Nonlinearity (DNL) ANALOG OUTPUT Offset Error Gain Error Without Internal Reference Gain Error with Internal Reference Gain Match TA = 25°C TMIN to TMAX TMIN to TMAX Full-Scale Output Current 2 Output Compliance Range Output Resistance Output Capacitance REFERENCE OUTPUT Reference Voltage Reference Output Current 3 REFERENCE INPUT Input Compliance Range Reference Input Resistance Small-Signal Bandwidth TEMPERATURE COEFFICIENTS Offset Drift Gain Drift Without Internal Reference Gain Drift with Internal Reference Reference Voltage Drift POWER SUPPLY Supply Voltages AVDD DVDD1, DVDD2 Analog Supply Current (IAVDD) Digital Supply Current (IDVDD) 4 Digital Supply Current (IDVDD) 5 Supply Current Sleep Mode (IAVDD) Power Dissipation4 (5 V, IOUTFS = 20 mA) Power Dissipation5 (5 V, IOUTFS = 20 mA) Power Dissipation 6 (5 V, IOUTFS = 20 mA) Power Supply Rejection Ratio 7 —AVDD Power Supply Rejection Ratio7—DVDD1, DVDD2 OPERATING RANGE Min 8 Typ Max Unit Bits −0.5 −0.5 ±0.1 ±0.1 +0.5 +0.5 LSB LSB −0.02 −2 −5 ±0.25 +1 +0.02 +2 +5 % of FSR % of FSR % of FSR +0.3 +1.6 +0.14 20.0 +1.25 % of FSR % of FSR dB mA V kΩ pF 1.26 V nA −0.3 −1.6 −0.14 2.0 −1.0 ±0.1 100 5 1.14 1.20 100 www.BDTIC.com/ADI 0.1 1.25 3 2.7 1 0.5 V MΩ MHz 0 ±50 ±100 ±50 ppm of FSR/°C ppm of FSR/°C ppm of FSR/°C ppm/°C 5 5 71 5 8 380 420 450 −0.4 −0.025 −40 1 5.5 5.5 75 7 15 12 410 450 +0.4 +0.025 +85 Measured at IOUTA, driving a virtual ground. Nominal full-scale current, IOUTFS, is 32 times the IREF current. An external buffer amplifier with input bias current <100 nA should be used to drive any external load. 4 Measured at fCLK = 25 MSPS and fOUT = 1.0 MHz. 5 Measured at fCLK = 100 MSPS and fOUT = 1 MHz. 6 Measured as unbuffered voltage output with IOUTFS = 20 mA and RLOAD = 50 Ω at IOUTA and IOUTB, fCLK = 100 MSPS, and fOUT = 40 MHz. 7 ±10% power supply variation. 2 3 B Rev. A | Page 3 of 32 V V mA mA mA mA mW mW mW % of FSR/V % of FSR/V °C AD9709 DYNAMIC SPECIFICATIONS TMIN to TMAX, AVDD = 3.3 V or 5 V, DVDD1 = DVDD2 = 3.3 V or 5 V, IOUTFS = 20 mA, differential transformer-coupled output, 50 Ω doubly terminated, unless otherwise noted. Table 2. Parameter DYNAMIC PERFORMANCE Maximum Output Update Rate (fCLK) Output Settling Time (tST) to 0.1% 1 Output Propagation Delay (tPD) Glitch Impulse Output Rise Time (10% to 90%)1 Output Fall Time (90% to 10%)1 Output Noise (IOUTFS = 20 mA) Output Noise (IOUTFS = 2 mA) AC LINEARITY Spurious-Free Dynamic Range to Nyquist fCLK = 100 MSPS, fOUT = 1.00 MHz 0 dBFS Output –6 dBFS Output –12 dBFS Output –18 dBFS Output fCLK = 65 MSPS, fOUT = 1.00 MHz fCLK = 65 MSPS, fOUT = 2.51 MHz fCLK = 65 MSPS, fOUT = 5.02 MHz fCLK = 65 MSPS, fOUT = 14.02 MHz fCLK = 65 MSPS, fOUT = 25 MHz fCLK = 125 MSPS, fOUT = 25 MHz fCLK = 125 MSPS, fOUT = 40 MHz Signal to Noise and Distortion Ratio fCLK = 50 MHz, fOUT = 1 MHz Total Harmonic Distortion fCLK = 100 MSPS, fOUT = 1.00 MHz fCLK = 50 MSPS, fOUT = 2.00 MHz fCLK = 125 MSPS, fOUT = 4.00 MHz fCLK = 125 MSPS, fOUT = 10.00 MHz Multitone Power Ratio (Eight Tones at 110 kHz Spacing) fCLK = 65 MSPS, fOUT = 2.00 MHz to 2.99 MHz 0 dBFS Output –6 dBFS Output –12 dBFS Output –18 dBFS Output Channel Isolation fCLK = 125 MSPS, fOUT = 10 MHz fCLK = 125 MSPS, fOUT = 40 MHz Min Typ Max 125 63 35 1 5 2.5 2.5 50 30 MSPS ns ns pV-s ns ns pA/√Hz pA/√Hz 68 62 56 50 68 68 66 60 50 63 55 dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc 50 dB www.BDTIC.com/ADI 1 −67 −63 −63 −63 Measured single-ended into 50 Ω load. Rev. A | Page 4 of 32 Unit −63 dBc dBc dBc dBc 58 51 46 41 dBc dBc dBc dBc 85 77 dBc dBc AD9709 DIGITAL SPECIFICATIONS TMIN to TMAX, AVDD = 3.3 V or 5 V, DVDD1 = DVDD2 = 3.3 V or 5 V IOUTFS = 20 mA, unless otherwise noted. Table 3. Parameter DIGITAL INPUTS Logic 1 Voltage @ DVDD1 = DVDD2 = 5 V Logic 1 Voltage @ DVDD1 = DVDD2 = 3.3 V Logic 0 Voltage @ DVDD1 = DVDD2 = 5 V Logic 0 Voltage @ DVDD1 = DVDD2 = 3.3 V Logic 1 Current Logic 0 Current Input Capacitance Input Setup Time (tS) Input Hold Time (tH) Latch Pulse Width (tLPW, tCPW) Min Typ 3.5 2.1 5 3 0 Max 1.3 0.9 +10 +10 0 −10 −10 5 2.0 1.5 3.5 Timing Diagram See Table 3 and the DAC Timing section for more information about the timing specifications. tS tH DATA IN (WRT2) (WRT1/IQWRT) tLPW www.BDTIC.com/ADI (CLK2) (CLK1/IQCLK) tPD Figure 2. Timing for Dual and Interleaved Modes Rev. A | Page 5 of 32 00606-002 tCPW IOUTA OR IOUTB Unit V V V V μA μA pF ns ns ns AD9709 ABSOLUTE MAXIMUM RATINGS Table 4. Parameter AVDD DVDD1, DVDD2 ACOM AVDD MODE, CLK1/IQCLK, CLK2/IQRESET, WRT1/IQWRT, WRT2/IQSEL Digital Inputs IOUTA1/IOUTA2, IOUTB1/IOUTB2 REFIO, FSADJ1, FSADJ2 GAINCTRL, SLEEP Junction Temperature Storage Temperature Range Lead Temperature (10 sec) With Respect To ACOM DCOM1/DCOM2 DCOM1/DCOM2 DVDD1/DVDD2 DCOM1/DCOM2 THERMAL RESISTANCE Rating −0.3 V to +6.5 V −0.3 V to +6.5 V −0.3 V to +0.3 V −6.5 V to +6.5 V −0.3 V to DVDD1/ DVDD2 + 0.3 V θJA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. Table 5. Thermal Resistance Package Type 48-Lead LQFP θJA 91 ESD CAUTION DCOM1/DCOM2 ACOM −0.3 V to DVDD1/ DVDD2 + 0.3 V −1.0 V to AVDD + 0.3 V ACOM −0.3 V to AVDD + 0.3 V ACOM −0.3 V to AVDD + 0.3 V 150°C −65°C to +150°C 300°C www.BDTIC.com/ADI Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Rev. A | Page 6 of 32 Unit °C/W AD9709 48 47 46 45 44 43 42 DB7P1 (MSB) 1 SLEEP ACOM IOUTA2 IOUTB2 FSADJ2 GAINCTRL REFIO FSADJ1 IOUTB1 IOUTA1 AVDD MODE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS 41 40 39 38 37 36 NC 35 NC DB5P1 3 34 NC DB4P1 4 33 NC DB3P1 5 32 NC DB2P1 6 31 NC DB1P1 7 30 DB0P2 (LSB) DB0P1 8 29 DB1P2 NC 9 28 DB2P2 NC 10 27 DB3P2 NC 11 26 DB4P2 NC 12 25 DB5P2 DB6P1 PIN 1 INDICATOR 2 AD9709 TOP VIEW (Not to Scale) 00606-003 DB6P2 DB7P2 (MSB) DVDD2 DCOM2 WRT2/IQSEL CLK2/IQRESET CLK1/IQCLK WRT1/IQWRT DVDD1 DCOM1 NC NC = NO CONNECT NC 13 14 15 16 17 18 19 20 21 22 23 24 Figure 3. Table 6. Pin Function Descriptions Pin No. 1 to 8 9 to 14, 31 to 36 15, 21 16, 22 17 18 19 20 23 to 30 37 38 39, 40 41 42 43 44 45, 46 47 48 Mnemonic DB7P1 to DB0P1 NC DCOM1, DCOM2 DVDD1, DVDD2 WRT1/IQWRT CLK1/IQCLK CLK2/IQRESET WRT2/IQSEL DB7P2 to DB0P2 SLEEP ACOM IOUTA2, IOUTB2 FSADJ2 GAINCTRL REFIO FSADJ1 IOUTB1, IOUTA1 AVDD MODE Description Data Bit Pins (Port 1) No Connection Digital Common Digital Supply Voltage Input Write Signal for Port 1 (IQWRT in Interleaving Mode) Clock Input for DAC1 (IQCLK in Interleaving Mode) Clock Input for DAC2 (IQRESET in Interleaving Mode) Input Write Signal for Port 2 (IQSEL in Interleaving Mode) Data Bit Pins (Port 2) Power-Down Control Input Analog Common Port 2 Differential DAC Current Outputs Full-Scale Current Output Adjust for DAC2 Master/Slave Resistor Control Mode. Reference Input/Output Full-Scale Current Output Adjust for DAC1 Port 1 Differential DAC Current Outputs Analog Supply Voltage Mode Select (1 = dual port, 0 = interleaved) www.BDTIC.com/ADI Rev. A | Page 7 of 32 AD9709 TYPICAL PERFORMANCE CHARACTERISTICS AVDD = 3.3 V or 5 V, DVDD = 3.3 V, IOUTFS = 20 mA, 50 Ω doubly terminated load, differential output, TA = 25°C, SFDR up to Nyquist, unless otherwise noted. 75 75 fCLK = 25MSPS 70 70 0dBFS 65 fCLK = 5MSPS SFDR (dBc) SFDR (dBc) 65 60 fCLK = 65MSPS 55 –6dBFS 60 55 –12dBFS fCLK = 125MSPS 100 fOUT (MHz) 45 0 5 10 35 60 70 35 70 0dBFS 0dBFS www.BDTIC.com/ADI 65 SFDR (dBc) 65 –6dBFS 60 –12dBFS 55 –6dBFS 60 –12dBFS 55 50 50 0.5 1.0 1.5 2.0 2.5 45 00606-006 0 fOUT (MHz) 0 10 20 30 40 50 fOUT (MHz) Figure 5. SFDR vs. fOUT @ 5 MSPS Figure 8. SFDR vs. fOUT @ 125 MSPS 75 75 70 70 IOUTFS = 20mA 0dBFS 65 SFDR (dBc) 65 –6dBFS 60 55 60 IOUTFS = 10mA 55 –12dBFS IOUTFS = 5mA 50 50 0 2 4 6 8 fOUT (MHz) 10 12 00606-007 SFDR (dBc) 30 75 70 45 25 Figure 7. SFDR vs. fOUT @ 65 MSPS 75 SFDR (dBc) 20 fOUT (MHz) Figure 4. SFDR vs. fOUT @ 0 dBFS 45 15 00606-008 10 00606-009 1 00606-005 45 0.1 00606-010 50 50 45 0 5 10 15 20 25 30 fOUT (MHz) Figure 9. SFDR vs. fOUT and IOUTFS @ 65 MSPS and 0 dBFS Figure 6. SFDR vs. fOUT @ 25 MSPS Rev. A | Page 8 of 32 AD9709 75 70 5MSPS/0.46MHz 70 10MSPS/0.91MHz 60 SINAD (dBc) 60 25MSPS/2.27MHz 65MSPS/5.91MHz 55 50 50 45 IOUTFS = 5mA 125MSPS/11.37MHz –22 –19 –16 –13 –10 –7 IOUTFS = 10mA –4 –1 2 AOUT (dBFS) 40 00606-011 40 –25 0 20 40 Figure 10. Single-Tone SFDR vs. AOUT @ fOUT = fCLK/11 80 100 120 140 Figure 13. SINAD vs. fCLK and IOUTFS @ fOUT = 5 MHz and 0 dBFS 75 0.06 0.04 70 5MSPS/1.0MHz 0.02 INL (LSBs) 65 60 10MSPS/2.0MHz 0 www.BDTIC.com/ADI 125MSPS/5.0MHz 55 50 –0.02 –0.04 –0.06 65MSPS/13.0MHz 45 25MSPS/5.0MHz –15 –10 –5 0 AOUT (dBFS) –0.10 00606-012 –20 0 32 64 96 128 160 192 224 256 00606-015 –0.08 40 –25 CODE Figure 11. Single-Tone SFDR vs. AOUT @ fOUT = fCLK/5 Figure 14. Typical INL 75 0.07 0.06 70 0.965MHz/1.035MHz @ 7MSPS 0.05 DNL (LSBs) 65 60 55 0.04 0.03 0.02 16.9MHz/19.1MHz @ 125MSPS 50 0.01 8.8MHz/9.8MHz @ 65MSPS 45 0 3.3MHz/3.4MHz @ 25MSPS 40 –25 –20 –15 –10 –5 AOUT (dBFS) 0 00606-013 SFDR (dBc) 60 fCLK (MSPS) 00606-014 45 SFDR (dBc) IOUTFS = 20mA 55 Figure 12. Dual-Tone SFDR vs. AOUT @ fOUT = fCLK/7 –0.01 0 50 100 150 CODE Figure 15. Typical DNL Rev. A | Page 9 of 32 200 250 00606-016 SFDR (dBc) 65 65 AD9709 75 0 –10 70 fOUT = 10MHz –30 fOUT = 25MHz 60 SFDR (dBm) SFDR (dBc) 65 –20 fOUT = 40MHz 55 –40 –50 –60 fOUT = 60MHz –70 50 –10 10 30 50 70 90 TEMPERATURE (°C) –90 0 20 30 40 50 60 60 FREQUENCY (MHz) Figure 16. SFDR vs. Temperature @ fCLK = 125 MSPS, 0 dBFS 0.05 10 00606-020 –30 00606-021 45 –50 00606-017 –80 Figure 19. Dual-Tone SFDR @ fCLK = 125 MSPS 0 1.0 GAIN ERROR –20 0.5 OFFSET ERROR –30 SFDR (dBm) GAIN ERROR (%FS) 0.03 –40 www.BDTIC.com/ADI 0 0 –0.03 –0.5 –50 –60 –70 –80 –20 0 20 40 60 –1.0 80 00606-018 –0.05 –40 TEMPERATURE (°C) Figure 17. Gain and Offset Error vs. Temperature @ fCLK = 125 MSPS –10 –20 –30 –40 –50 –60 –70 –80 0 10 20 30 40 50 FREQUENCY (MHz) 60 00606-019 –90 –100 –90 0 10 20 30 40 50 FREQUENCY (MHz) Figure 20. Four-Tone SFDR @ fCLK = 125 MSPS 0 SFDR (dBm) OFFSET ERROR (%FS) –10 Figure 18. Single-Tone SFDR @ fCLK = 125 MSPS Rev. A | Page 10 of 32 AD9709 TERMINOLOGY Linearity Error (Integral Nonlinearity or INL) Linearity error is defined as the maximum deviation of the actual analog output from the ideal output, determined by a straight line drawn from zero to full-scale. Differential Nonlinearity (DNL) DNL is the measure of the variation in analog value, normalized to full scale, associated with a 1 LSB change in digital input code. Monotonicity A DAC is monotonic if the output either increases or remains constant as the digital input increases. Offset Error Offset error is the deviation of the output current from the ideal of zero. For IOUTA, 0 mA output is expected when the inputs are all 0s. For IOUTB, 0 mA output is expected when all inputs are set to 1s. Temperature Drift Temperature drift is specified as the maximum change from the ambient (25°C) value to the value at either TMIN or TMAX. For offset and gain drift, the drift is reported in part per million (ppm) of full-scale range (FSR) per degree Celsius. For reference drift, the drift is reported in ppm per degree Celsius (pm/°C). Power Supply Rejection (PSR) PSR is the maximum change in the full-scale output as the supplies are varied from nominal to minimum and maximum specified voltages. Settling Time Settling time is the time required for the output to reach and remain within a specified error band about its final value, measured from the start of the output transition. B Gain Error Gain error is the difference between the actual and ideal output spans. The actual span is determined by the output when all inputs are set to 1s minus the output when all inputs are set to 0s. Output Compliance Range The output compliance range is 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. Glitch Impulse Asymmetrical switching times in a DAC give rise to undesired output transients that are quantified by a glitch impulse. It is specified as the net area of the glitch in picovolts per second (pV-s). Spurious-Free Dynamic Range The difference, in decibels (dB), between the rms amplitude of the output signal and the peak spurious signal over the specified bandwidth. www.BDTIC.com/ADI 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. It is expressed as a percentage or in decibels (dB). Rev. A | Page 11 of 32 AD9709 THEORY OF OPERATION 5V CLK1/IQCLK CLK2/IQRESET AVDD RSET1 2kΩ REFIO PMOS CURRENT SOURCE ARRAY FSADJ2 PMOS CURRENT SOURCE ARRAY 0.1µF RSET 2 2kΩ GAINCTRL DVDD1/DVDD2 DCOM1/DCOM2 RETIMED CLOCK OUTPUT* IOUTA1 WRT1/ IQWRT 50Ω SEGMENTED LSB SWITCHES FOR SWITCH IOUTB1 DAC1 DAC1 LATCH DAC2 LATCH TO HP3589A OR EQUIVALENT SPECTRUM/ NETWORK ANALYZER 50Ω IOUTA2 SEGMENTED LSB SWITCHES FOR SWITCH IOUTB2 DAC2 MODE MULTIPLEXING LOGIC 1.2V REF Mini-Circuits T1-1T AD9709 CLK DIVIDER CHANNEL 1 LATCH CHANNEL 2 LATCH PORT 1 PORT 2 50Ω DVDD1/ DCOM1/ DVDD2 DCOM2 ACOM 5V WRT2/ IQSEL DIGITAL DATA LECROY 9210 PULSE GENERATOR *AWG2021 CLOCK RETIMED SUCH THAT DIGITAL DATA TRANSITIONS ON FALLING EDGE OF 50% DUTY CYCLE CLOCK. TEKTRONIX AWG2021 WITH OPTION 4 00606-004 FSADJ1 SLEEP Figure 21. Basic AC Characterization Test Setup for AD9709, Testing Port 1 in Dual Port Mode, Using Independent GAINCTRL Resistors on FSADJ1 and FSADJ2 5V CLK1/IQCLK CLK2/IQRESET AVDD IREF 1 0.1µF RSET 2 2kΩ FSADJ1 REFIO SLEEP PMOS CURRENT SOURCE ARRAY VDIFF = VOUTA – VOUTB CLK DIVIDER www.BDTIC.com/ADI FSADJ2 IREF 2 1.2V REF PMOS CURRENT SOURCE ARRAY AD9709 DAC1 LATCH DAC2 LATCH WRT1/ IQWRT IOUTA2 SEGMENTED LSB SWITCHES FOR IOUTB2 SWITCH DAC2 DVDD1/ DVDD2 MULTIPLEXING LOGIC CHANNEL 1 LATCH GAINCTRL VOUT1A IOUTA1 SEGMENTED LSB SWITCHES FOR I SWITCH OUTB1 DAC1 VOUT2A VOUT2B 5V RL2B 50Ω RL1B 50Ω RL1A 50Ω RL2A 50Ω ACOM DCOM1/ DCOM2 CHANNEL 2 LATCH PORT 1 PORT 2 DIGITAL DATA INPUTS VOUT1B WRT2/ IQSEL MODE 00606-022 RSET 1 2kΩ Figure 22. Simplified Block Diagram FUNCTIONAL DESCRIPTION All of these current sources are switched to one of the two output nodes (that is, IOUTA or IOUTB) via the PMOS differential current switches. The switches are based on a new architecture that drastically improves distortion performance. This new switch architecture reduces various timing errors and provides matching of complementary drive signals to the inputs of the differential current switches. B Figure 22 shows a simplified block diagram of the AD9709. The AD9709 consists of two DACs, each one with its own independent digital control logic and full-scale output current control. Each DAC contains a PMOS current source array capable of providing up to 20 mA of full-scale current (IOUTFS). The array is divided into 31 equal currents that make up the five most significant bits (MSBs). The next four bits, or middle bits, consist of 15 equal current sources whose value is 1/16th of an MSB current source. The remaining LSB is a binary weighted fraction of the middle bit current sources. Implementing the middle and lower bits with current sources instead of an R-2R ladder enhances the dynamic performance for multitone or low amplitude signals and helps maintain the high output impedance of each DAC (that is, >100 kΩ). The analog and digital sections of the AD9709 have separate power supply inputs (that is, AVDD and DVDD1/DVDD2) that can operate independently over a 3.3 V to 5 V range. The digital section, which is capable of operating up to a 125 MSPS clock rate, consists of edge-triggered latches and segment decoding logic circuitry. The analog section includes the PMOS current sources, the associated differential switches, a 1.20 V band gap voltage reference, and two reference control amplifiers. Rev. A | Page 12 of 32 AD9709 The full-scale output current of each DAC is regulated by separate reference control amplifiers and can be set from 2 mA to 20 mA via an external network connected to the full-scale adjust (FSADJ) pin. The external network in combination with both the reference control amplifier and voltage reference (VREFIO) sets the reference current (IREF), which is replicated to the segmented current sources with the proper scaling factor. The full-scale current (IOUTFS) is 32 × IREF. GAIN CONTROL MODE The AD9709 allows the gain of each channel to be set independently by connecting one RSET resistor to FSADJ1 and another RSET resistor to FSADJ2. To add flexibility and reduce system cost, a single RSET resistor can be used to set the gain of both channels simultaneously. REFERENCE OPERATION The AD9709 contains an internal 1.20 V band gap reference. This can easily be overridden by a low noise external reference with no effect on performance. REFIO serves as either an input or output depending on whether the internal or an external reference is used. To use the internal reference, simply decouple the REFIO pin to ACOM with a 0.1 μF capacitor. The internal reference voltage will be present at REFIO. If the voltage at REFIO is to be used elsewhere in the circuit, an external buffer amplifier with an input bias current of less than 100 nA should be used. An example of the use of the internal reference is shown in Figure 23. OPTIONAL EXTERNAL REFERENCE BUFFER GAINCTRL REFERENCE SECTION REFIO 0.1µF RSET FSADJ1/ FSADJ2 I REF = ACOM 22nF Figure 23. Internal Reference Configuration An external reference can be applied to REFIO as shown in Figure 24. The external reference can provide either a fixed reference voltage to enhance accuracy and drift performance or a varying reference voltage for gain control. Note that the 0.1 μF compensation capacitor is not required because the internal reference is overridden and the relatively high input impedance of REFIO minimizes any loading of the external reference. GAINCTRL 1.2V REF REFIO EXTERNAL REFERENCE 256Ω IREF RSET FSADJ1/ FSADJ2 AVDD AD9709 REFERENCE SECTION CURRENT SOURCE ARRAY 22nF Figure 24. External Reference Configuration ACOM 00606-024 AVDD SETTING THE FULL-SCALE CURRENT www.BDTIC.com/ADI 256Ω IREF CURRENT SOURCE ARRAY 00606-023 ADDITIONAL EXTERNAL LOAD Note that only parts with a date code of 9930 or later have the master/slave gain control function. For parts with a date code before 9930, Pin 42 must be connected to AGND, and the part operates in the two-resistor, independent gain control mode. Both of the DACs in the AD9709 contain a control amplifier that is used to regulate the full-scale output current (IOUTFS). The control amplifier is configured as a V-I converter, as shown in Figure 23, so that its current output (IREF) is determined by the ratio of the VREFIO and an external resistor, RSET. AVDD AD9709 1.2V REF When GAINCTRL is low (that is, connected to analog ground), the independent channel gain control mode using two resistors is enabled. In this mode, individual RSET resistors should be connected to FSADJ1 and FSADJ2. When GAINCTRL is high (that is, connected to AVDD), the master/slave channel gain control mode using one network is enabled. In this mode, a single network is connected to FSADJ1, and the FSADJ2 pin must be left unconnected. VREFIO RSET The DAC full-scale current, IOUTFS, is an output current 32 times larger than the reference current, IREF. I OUTFS = 32 × I REF The control amplifier allows a wide (10:1) adjustment span of IOUTFS from 2 mA to 20 mA by setting IREF between 62.5 μA and 625 μA. The wide adjustment range of IOUTFS provides several benefits. The first relates directly to the power dissipation of the AD9709, which is proportional to IOUTFS (refer to the Power Dissipation section). The second relates to the 20 dB adjustment, which is useful for system gain control purposes. It should be noted that when the RSET resistors are 2 kΩ or less, the 22 nF capacitor and 256 Ω resistor shown in Figure 23 and Figure 24 are not required and the reference current can be set by the RSET resistors alone. For RSET values greater than 2 kΩ, the 22 nF capacitor and 256 Ω resistor networks are required to ensure the stability of the reference control amplifier(s). Regardless of the value of RSET, however, if the RSET resistor is located more than ~10 cm away from the pin, use of the 22 nF capacitor and 256 Ω resistor is recommended. Rev. A | Page 13 of 32 AD9709 DAC TRANSFER FUNCTION Both DACs in the AD9709 provide complementary current outputs, IOUTA and IOUTB. IOUTA provides a near full-scale current output, IOUTFS, when all bits are high (that is, DAC CODE = 256) while IOUTB, the complementary output, provides no current. The current output appearing at IOUTA and IOUTB is a function of both the input code and IOUTFS and can be expressed as B IOUTA = (DAC CODE/256) × IOUTFS (1) IOUTB = (255 − DAC CODE)/256 × IOUTFS (2) where DAC CODE = 0 to 255 (that is, decimal representation). IOUTFS is a function of the reference current (IREF), which is nominally set by a reference voltage (VREFIO) and an external resistor (RSET). It can be expressed as IOUTFS = 32 × IREF (3) where IREF = VREFIO/RSET (4) The two current outputs typically drive a resistive load directly or via a transformer. If dc coupling is required, IOUTA and IOUTB should be connected directly to matching resistive loads, RLOAD, that are tied to the analog common, ACOM. Note that RLOAD can represent the equivalent load resistance seen by IOUTA or IOUTB, as would be the case in a doubly terminated 50 Ω or 75 Ω cable. The single-ended voltage output appearing at the IOUTA and IOUTB nodes is B B VOUTA = IOUTA × RLOAD differential amplifier configuration. The ac performance of the AD9709 is optimum and specified using a differential transformer-coupled output in which the voltage swing at IOUTA and IOUTB is limited to ±0.5 V. If a single-ended unipolar output is desirable, IOUTA should be selected. B The distortion and noise performance of the AD9709 can be enhanced when it is configured for differential operation. The common-mode error sources of both IOUTA and IOUTB can be significantly reduced by the common-mode rejection of a transformer or differential amplifier. These common-mode error sources include even-order distortion products and noise. The enhancement in distortion performance becomes more significant as the frequency content of the reconstructed waveform increases. This is due to the first-order cancellation of various dynamic common-mode distortion mechanisms, digital feedthrough, and noise. B Performing a differential-to-single-ended conversion via a transformer also provides the ability to deliver twice the reconstructed signal power to the load (that is, assuming no source termination). Because the output currents of IOUTA and IOUTB are complementary, they become additive when processed differentially. A properly selected transformer allows the AD9709 to provide the required power and voltage levels to different loads. B The output impedance of IOUTA and IOUTB is determined by the equivalent parallel combination of the PMOS switches associated with the current sources and is typically 100 kΩ in parallel with 5 pF. It is also slightly dependent on the output voltage (that is, VOUTA and VOUTB) due to the nature of a PMOS device. As a result, maintaining IOUTA and/or IOUTB at a virtual ground via an I-V op amp configuration results in the optimum dc linearity. Note that the INL/DNL specifications for the AD9709 are measured with IOUTA maintained at a virtual ground via an op amp. www.BDTIC.com/ADI VOUTB = IOUTB × RLOAD (5) (6) B B Note the full-scale value of VOUTA and VOUTB must not exceed the specified output compliance range to maintain the specified distortion and linearity performance. VDIFF = (IOUTA − IOUTB) × RLOAD (7) Equation 7 highlights some of the advantages of operating the AD9709 differentially. First, the differential operation helps cancel common-mode error sources associated with IOUTA and IOUTB, such as noise, distortion, and dc offsets. Second, the differential code-dependent current and subsequent voltage, VDIFF, is twice the value of the single-ended voltage output (that is, VOUTA or VOUTB), thus providing twice the signal power to the load. IOUTA and IOUTB also have a negative and positive voltage compliance range that must be adhered to in order to achieve optimum performance. The negative output compliance range of −1.0 V is set by the breakdown limits of the CMOS process. Operation beyond this maximum limit may result in a breakdown of the output stage and affect the reliability of the AD9709. Note that the gain drift temperature performance for a singleended (VOUTA and VOUTB) or differential output (VDIFF) of the AD9709 can be enhanced by selecting temperature tracking resistors for RLOAD and RSET due to their ratiometric relationship. The positive output compliance range is slightly dependent on the full-scale output current, IOUTFS. When IOUTFS is decreased from 20 mA to 2 mA, the positive output compliance range degrades slightly from its nominal 1.25 V to 1.00 V. The optimum distortion performance for a single-ended or differential output is achieved when the maximum full-scale signal at IOUTA and IOUTB does not exceed 0.5 V. Applications requiring the AD9709 output (that is, VOUTA and/or VOUTB) to extend its output compliance range should size RLOAD accordingly. Operation beyond this compliance range adversely affects the linearity performance of the AD9709 and subsequently degrade its distortion performance. B B ANALOG OUTPUTS The complementary current outputs, IOUTA and IOUTB, in each DAC can be configured for single-ended or differential operation. IOUTA and IOUTB can be converted into complementary single-ended voltage outputs, VOUTA and VOUTB, via a load resistor, RLOAD, as described in Equation 5 through Equation 7. The differential voltage, VDIFF, existing between VOUTA and VOUTB can be converted to a single-ended voltage via a transformer or B B Rev. A | Page 14 of 32 AD9709 The digital interface is implemented using an edge-triggered master slave latch. The DAC outputs are updated following either the rising edge or every other rising edge of the clock, depending on whether dual or interleaved mode is used. The DAC outputs are designed to support a clock rate as high as 125 MSPS. The clock can be operated at any duty cycle that meets the specified latch pulse width. The setup and hold times can also be varied within the clock cycle as long as the specified minimum times are met, although the location of these transition edges may affect digital feedthrough and distortion performance. Best performance is typically achieved when the input data transitions on the falling edge of a 50% duty cycle clock. DAC TIMING tH DATA IN WRT1/WRT2 tLPW CLK1/CLK2 tCPW IOUTA OR IOUTB tPD Figure 26. Dual Port Mode Timing DATA IN D1 D2 D3 D4 D5 WRT1/WRT2 CLK1/CLK2 IOUTA OR IOUTB XX D1 D2 D3 D4 Figure 27. Dual Mode Timing Interleaved Mode Timing PORT 1 INPUT LATCH When the MODE pin is at Logic 0, the AD9709 operates in interleaved mode (refer to Figure 25). In addition, WRT1 functions as IQWRT, CLK1 functions as IQCLK, WRT2 functions as IQSEL, and CLK2 functions as IQRESET. DAC1 LATCH DAC1 IQCLK IQRESET ÷2 DEINTERLEAVED DATA OUT DAC2 LATCH 00606-027 PORT 2 INPUT LATCH IQWRT IQSEL tS www.BDTIC.com/ADI The AD9709 can operate in two timing modes, dual and interleaved, which are described in the following sections. The block diagram in Figure 25 represents the latch architecture in the interleaved timing mode. INTERLEAVED DATA IN, PORT 1 Timing specifications for dual port mode are given in Figure 26 and Figure 27. 00606-025 The digital inputs of the AD9709 consist of two independent channels. For the dual port mode, each DAC has its own dedicated 8-bit data port: WRT line and CLK line. In the interleaved timing mode, the function of the digital control pins changes as described in the Interleaved Mode Timing section. The 8-bit parallel data inputs follow straight binary coding where DB7P1 and DB7P2 are the most significant bits (MSBs) and DB0P1 and DB0P2 are the least significant bits (LSBs). IOUTA produces a full-scale output current when all data bits are at Logic 1. IOUTB produces a complementary output with the full-scale current split between the two outputs as a function of the input code. The rising edge of CLK should occur before or simultaneously with the rising edge of WRT. If the rising edge of CLK occurs after the rising edge of WRT, a minimum delay of 2 ns should be maintained from rising edge of WRT to rising edge of CLK. 00606-026 DIGITAL INPUTS DAC2 Figure 25. Latch Structure in Interleaved Mode Dual Port Mode Timing When the MODE pin is at Logic 1, the AD9709 operates in dual port mode (refer to Figure 21). The AD9709 functions as two distinct DACs. Each DAC has its own completely independent digital input and control lines. The AD9709 features a double-buffered data path. Data enters the device through the channel input latches. This data is then transferred to the DAC latch in each signal path. After the data is loaded into the DAC latch, the analog output settles to its new value. For general consideration, the WRT lines control the channel input latches, and the CLK lines control the DAC latches. Both sets of latches are updated on the rising edge of their respective control signals. Data enters the device on the rising edge of IQWRT. The logic level of IQSEL steers the data to either Channel Latch 1 (IQSEL = 1) or to Channel Latch 2 (IQSEL = 0). For proper operation, IQSEL should only change state when IQWRT and IQCLK are low. When IQRESET is high, IQCLK is disabled. When IQRESET goes low, the next rising edge on IQCLK updates both DAC latches with the data present at their inputs. In the interleaved mode, IQCLK is divided by 2 internally. Following this first rising edge, the DAC latches are only updated on every other rising edge of IQCLK. In this way, IQRESET can be used to synchronize the routing of the data to the DACs. Similar to the order of CLK and WRT in dual port mode, IQCLK should occur before or simultaneously with IQWRT. Timing specifications for interleaved mode are shown in Figure 28 and Figure 30. The digital inputs are CMOS compatible with logic thresholds, VTHRESHOLD, set to approximately half the digital positive supply (DVDDx) or Rev. A | Page 15 of 32 VTHRESHOLD = DVDDx/2 (±20%) AD9709 tS tH INTERLEAVED DATA xx D1 D2 D3 D4 D5 IQSEL DATA IN 500 ps IQWRT IQSEL IQRESET tH* tLPW DAC OUTPUT PORT 1 IQCLK IOUTA OR IOUTB 00606-056 *APPLIES TO FALLING EDGE OF IQCLK/IQWRT AND IQSEL ONLY. Figure 28. 5 V or 3.3 V Interleaved Mode Timing At 5 V it is permissible to drive IQWRT and IQCLK together as shown in Figure 29, but at 3.3 V the interleaved data transfer is not reliable. tS tH The internal digital circuitry of the AD9709 is capable of operating at a digital supply of 3.3 V or 5 V. As a result, the digital inputs can also accommodate TTL levels when DVDD1/DVDD2 is set to accommodate the maximum high level voltage (VOH(MAX)) of the TTL drivers. A DVDD1/DVDD2 of 3.3 V typically ensures proper compatibility with most TTL logic families. Figure 31 shows the equivalent digital input circuit for the data and clock inputs. The sleep mode input is similar with the exception that it contains an active pull-down circuit, thus ensuring that the AD9709 remains enabled if this input is left disconnected. www.BDTIC.com/ADI DVDD1 DIGITAL INPUT 00606-030 IQSEL tH* Figure 31. Equivalent Digital Input tLPW IQCLK tPD *APPLIES TO FALLING EDGE OF IQCLK/IQWRT AND IQSEL ONLY. Figure 29. 5 V Only Interleaved Mode Timing 00606-028 IOUTA OR IOUTB D4 D2 Figure 30. Interleaved Mode Timing tPD DATA IN D3 D1 xx DAC OUTPUT PORT 2 500 ps IQWRT xx 00606-029 IQWRT IQCLK Because the AD9709 is capable of being clocked up to 125 MSPS, the quality of the clock and data input signals are important in achieving the optimum performance. Operating the AD9709 with reduced logic swings and a corresponding digital supply (DVDD1/DVDD2) results in the lowest data feedthrough and on-chip digital noise. The drivers of the digital data interface circuitry should be specified to meet the minimum setup and hold times of the AD9709 as well as its required minimum and maximum input logic level thresholds. Rev. A | Page 16 of 32 AD9709 Note that the clock input can also be driven via a sine wave, which is centered around the digital threshold (that is, DVDDx/2) and meets the minimum and maximum logic threshold. This typically results in a slight degradation in the phase noise, which becomes more noticeable at higher sampling rates and output frequencies. In addition, at higher sampling rates, the 20% tolerance of the digital logic threshold should be considered because it affects the effective clock duty cycle and, subsequently, cut into the required data setup and hold times. SNR in a DAC is dependent on the relationship between the position of the clock edges and the point in time at which the input data changes. The AD9709 is rising-edge triggered and therefore exhibits SNR sensitivity when the data transition is close to this edge. In general, the goal when applying the AD9709 is to make the data transition close to the falling clock edge. This becomes more important as the sample rate increases. Figure 32 shows the relationship of SNR to clock/data placement. 60 50 40 30 20 10 0 –4 –3 –2 –1 0 1 2 TIME OF DATA CHANGE RELATIVE TO RISING CLOCK EDGE (ns) 3 4 00606-031 The external clock driver circuitry provides the AD9709 with a low-jitter clock input meeting the minimum and maximum logic levels while providing fast edges. Fast clock edges help minimize jitter manifesting itself as phase noise on a reconstructed waveform. Therefore, the clock input should be driven by the fastest logic family suitable for the application. Input Clock and Data Timing Relationship SNR (dBc) Digital signal paths should be kept short, and run lengths should be matched to avoid propagation delay mismatch. The insertion of a low value (that is, 20 Ω to 100 Ω) resistor network between the AD9709 digital inputs and driver outputs may be helpful in reducing any overshooting and ringing at the digital inputs that contribute to digital feedthrough. For longer board traces and high data update rates, stripline techniques with proper impedance and termination resistors should be considered to maintain “clean” digital inputs. Figure 32. SNR vs. Clock Placement @ fOUT = 20 MHz and fCLK = 125 MSPS www.BDTIC.com/ADI Rev. A | Page 17 of 32 AD9709 SLEEP MODE OPERATION 80 The AD9709 has a power-down function that turns off the output current and reduces the supply current to less than 8.5 mA over the specified supply range of 3.3 V to 5 V and temperature range. This mode can be activated by applying a Logic Level 1 to the SLEEP pin. The SLEEP pin logic threshold is equal to 0.5 × AVDD. This digital input also contains an active pull-down circuit that ensures the AD9709 remains enabled if this input is left disconnected. The AD9709 requires less than 50 ns to power down and approximately 5 μs to power back up. 70 IAVDD (mA) 60 50 40 30 20 5 10 15 20 25 0.4 0.5 00606-033 • • • • 0 0.5 00606-034 10 The power dissipation, PD, of the AD9709 is dependent on several factors, including 00606-032 POWER DISSIPATION IOUTFS (mA) Figure 33. IAVDD vs. IOUTFS the power supply voltages (AVDD and DVDD1/DVDD2) the full-scale current output (IOUTFS) the update rate (fCLK) the reconstructed digital input waveform 35 30 125MSPS 25 100MSPS IDVDD (mA) The power dissipation is directly proportional to the analog supply current, IAVDD, and the digital supply current, IDVDD. IAVDD is directly proportional to IOUTFS, as shown in Figure 33, and is insensitive to fCLK. Conversely, IDVDD is dependent on the digital input waveform, fCLK, and digital supply (DVDD1/DVDD2). Figure 34 and Figure 35 show IDVDD as a function of full-scale sine wave output ratios (fOUT/fCLK) for various update rates with DVDD1 = DVDD2 = 5 V and DVDD1 = DVDD2 = 3.3 V, respectively. Note how IDVDD is reduced by more than a factor of 2 when DVDD1/DVDD2 is reduced from 5 V to 3.3 V. 20 65MSPS 15 10 25MSPS www.BDTIC.com/ADI 5 5MSPS 0 0 0.1 0.2 0.3 RATIO (fOUT/fCLK) Figure 34. IDVDD vs. Ratio @ DVDD1 = DVDD2 = 5 V 18 125MSPS 16 14 100MSPS IDVDD (mA) 12 10 65MSPS 8 6 25MSPS 4 5MSPS 2 0 0 0.1 0.2 0.3 0.4 RATIO (fOUT/fCLK) Figure 35. IDVDD vs. Ratio @ DVDD1 = DVDD2 = 3.3 V Rev. A | Page 18 of 32 AD9709 APPLYING THE AD9709 The following sections illustrate some typical output configurations for the AD9709. Unless otherwise noted, it is assumed that IOUTFS is set to a nominal 20 mA. For applications requiring the optimum dynamic performance, a differential output configuration is suggested. A differential output configuration can consist of either an RF transformer or a differential op amp configuration. The transformer configuration provides the optimum high frequency performance and is recommended for any application allowing for ac coupling. The differential op amp configuration is suitable for applications requiring dc coupling, bipolar output, signal gain, and/or level shifting, within the bandwidth of the chosen op amp. A single-ended output is suitable for applications requiring a unipolar voltage output. A positive unipolar output voltage results if IOUTA and/or IOUTB is connected to an appropriately sized load resistor, RLOAD, referred to ACOM. This configuration may be more suitable for a single-supply system requiring a dc-coupled, ground-referred output voltage. Alternatively, an amplifier can be configured as an I-V converter, thus converting IOUTA or IOUTB into a negative unipolar voltage. This configuration provides the best dc linearity because IOUTA or IOUTB is maintained at a virtual ground. Note that IOUTA provides slightly better performance than IOUTB. B output compliance range of the AD9709. A differential resistor, RDIFF, can be inserted in applications where the output of the transformer is connected to the load, RLOAD, via a passive reconstruction filter or cable. RDIFF is determined by the transformer’s impedance ratio and provides the proper source termination that results in a low VSWR. Note that approximately half the signal power will be dissipated across RDIFF. DIFFERENTIAL COUPLING USING AN OP AMP An op amp can also be used as shown in Figure 37 to perform a differential-to-single-ended conversion. The AD9709 is configured with two equal load resistors, RLOAD, of 25 Ω each. The differential voltage developed across IOUTA and IOUTB is converted to a singleended signal via the differential op amp configuration. An optional capacitor can be installed across IOUTA and IOUTB, forming a real pole in a low-pass filter. The addition of this capacitor also enhances the op amp’s distortion performance by preventing the DAC’s highslewing output from overloading the op amp’s input. B 500Ω AD9709 225Ω IOUTA B COPT www.BDTIC.com/ADI DIFFERENTIAL COUPLING USING A TRANSFORMER 500Ω 25Ω RLOAD OPTIONAL RDIFF The differential circuit shown in Figure 38 provides the necessary level shifting required in a single-supply system. In this case, AVDD, which is the positive analog supply for both the AD9709 and the op amp, is used to level shift the differential output of the AD9709 to midsupply (that is, AVDD/2). The AD8041 is a suitable op amp for this application. 500Ω AD9709 00606-035 IOUTB The common-mode rejection of this configuration is typically determined by the resistor matching. In this circuit, the differential op amp circuit using the AD8047 is configured to provide some additional signal gain. The op amp must operate from a dual supply because its output is approximately ±1.0 V. A high speed amplifier capable of preserving the differential performance of the AD9709 while meeting other system level objectives (that is, cost and power) should be selected. The op amp’s differential gain, gain setting resistor values, and full-scale output swing capabilities should be considered when optimizing this circuit. 225Ω IOUTA Figure 36. Differential Output Using a Transformer 225Ω IOUTB The center tap on the primary side of the transformer must be connected to ACOM to provide the necessary dc current path for both IOUTA and IOUTB. The complementary voltages appearing at IOUTA and IOUTB (that is, VOUTA and VOUTB) swing symmetrically around ACOM and should be maintained with the specified AD8041 COPT 25Ω 1kΩ 25Ω AVDD 500Ω B Rev. A | Page 19 of 32 Figure 38. Single-Supply DC Differential Coupled Circuit 00606-037 Mini-Circuits T1-1T IOUTA 25Ω Figure 37. DC Differential Coupling Using an Op Amp An RF transformer can be used as shown in Figure 36 to perform a differential-to-single-ended signal conversion. A differentially coupled transformer output provides the optimum distortion performance for output signals whose spectral content lies within the pass band of the transformer. An RF transformer such as the Mini-Circuits® T1-1T provides excellent rejection of commonmode distortion (that is, even-order harmonics) and noise over a wide frequency range. It also provides electrical isolation and the ability to deliver twice the power to the load. Transformers with different impedance ratios can also be used for impedance matching purposes. Note that the transformer provides ac coupling only. AD9709 AD8047 225Ω IOUTB B 00606-036 OUTPUT CONFIGURATIONS AD9709 SINGLE-ENDED, UNBUFFERED VOLTAGE OUTPUT Figure 39 shows the AD9709 configured to provide a unipolar output range of approximately 0 V to 0.5 V for a doubly terminated 50 Ω cable, because the nominal full-scale current, IOUTFS, of 20 mA flows through the equivalent RLOAD of 25 Ω. In this case, RLOAD represents the equivalent load resistance seen by IOUTA or IOUTB. The unused output (IOUTA or IOUTB) can be connected directly to ACOM or via a matching RLOAD. Different values of IOUTFS and RLOAD can be selected as long as the positive compliance range is adhered to. One additional consideration in this mode is the INL (see the Analog Outputs section). For optimum INL performance, the single-ended, buffered voltage output configuration is suggested. as important as the circuit design. Proper RF techniques must be used for device selection, placement, and routing as well as power supply bypassing and grounding to ensure optimum performance. Figure 49 to Figure 54 illustrate the recommended printed circuit board ground, power, and signal plane layouts that are implemented on the AD9709 evaluation board. B B AD9709 IOUTFS = 20mA VOUTA = 0V TO 0.5V IOUTA 50Ω 50Ω 00606-038 IOUTB 25Ω One factor that can measurably affect system performance is the ability of the DAC output to reject dc variations or ac noise superimposed on the analog or digital dc power distribution. This is referred to as the power supply rejection ratio (PSRR). For dc variations of the power supply, the resulting performance of the DAC directly corresponds to a gain error associated with the DAC’s full-scale current, IOUTFS. AC noise on the dc supplies is common in applications where the power distribution is generated by a switching power supply. Typically, switching power supply noise occurs over the spectrum from tens of kilohertz to several megahertz. The PSRR vs. frequency of the AD9709 AVDD supply over this frequency range is shown in Figure 41. 90 Figure 39. 0 V to 0.5 V Unbuffered Voltage Output SINGLE-ENDED, BUFFERED VOLTAGE OUTPUT CONFIGURATION PSRR (dB) 85 Figure 40 shows a buffered single-ended output configuration in which the U1 op amp performs an I-V conversion on the AD9709 output current. U1 maintains IOUTA (or IOUTB) at a virtual ground, thus minimizing the nonlinear output impedance effect on the INL performance of the DAC, as discussed in the Analog Outputs section. Although this singleended configuration typically provides the best dc linearity performance, its ac distortion performance at higher DAC update rates may be limited by the slewing capabilities of U1. U1 provides a negative unipolar output voltage, and its fullscale output voltage is simply the product of RFB and IOUTFS. The full-scale output should be set within U1’s voltage output swing capabilities by scaling IOUTFS and/or RFB. An improvement in ac distortion performance may result with a reduced IOUTFS because the signal current U1 has to sink will be subsequently reduced. www.BDTIC.com/ADI B COPT RFB 200Ω AD9709 IOUTFS = 10mA IOUTA U1 200Ω 00606-039 VOUT = IOUTFS × RFB IOUTB Figure 40. Unipolar Buffered Voltage Output POWER AND GROUNDING CONSIDERATIONS Power Supply Rejection Many applications seek high speed and high performance under less than ideal operating conditions. In these applications, the implementation and construction of the printed circuit board is 80 70 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 FREQUENCY (MHz) 00606-040 75 Figure 41. AVDD Power Supply Rejection Ratio vs. Frequency Note that the data in Figure 41 is given in terms of current out vs. voltage in. Noise on the analog power supply has the effect of modulating the internal current sources and therefore the output current. The voltage noise on AVDD, therefore, is added in a nonlinear manner to the desired IOUT. PSRR is very code dependent, thus producing mixing effects that can modulate low frequency power supply noise to higher frequencies. Worstcase PSRR for either one of the differential DAC outputs occurs when the full-scale current is directed toward that output. As a result, the PSRR measurement in Figure 41 represents a worstcase condition in which the digital inputs remain static and the full-scale output current of 20 mA is directed to the DAC output being measured. An example serves to illustrate the effect of supply noise on the analog supply. Suppose a switching regulator with a switching frequency of 250 kHz produces 10 mV of noise and, for simplicity’s sake, all of this noise is concentrated at 250 kHz (that is, ignore harmonics). To calculate how much of this undesired noise will appear as current noise superimposed on the DAC full-scale Rev. A | Page 20 of 32 AD9709 Proper grounding and decoupling should be a primary objective in any high speed, high resolution system. The AD9709 features separate analog and digital supply and ground pins to optimize the management of analog and digital ground currents in a system. In general, decouple the analog supply (AVDD) to the analog common (ACOM) as close to the chip as physically possible. Similarly, decouple DVDD1/DVDD2, the digital supply (DVDD1/DVDD2) to the digital common (DCOM1/DCOM2) as close to the chip as possible. For applications that require a single 5 V or 3.3 V supply for both the analog and digital supplies, a clean analog supply can be generated using the circuit shown in Figure 42. The circuit consists of a differential LC filter with separate power supply and return lines. Lower noise can be attained by using low-ESR type electrolytic and tantalum capacitors. FERRITE BEADS ELECTROLYTIC TTL/CMOS LOGIC CIRCUITS 10µF TO 22µF AVDD 0.1µF ACOM TANTALUM 5V POWER SUPPLY Figure 42. Differential LC Filter for Single 5 V and 3.3 V Applications www.BDTIC.com/ADI Rev. A | Page 21 of 32 100µF CERAMIC 00606-041 current, IOUTFS, one must determine the PSRR in decibels using Figure 41 at 250 kHz. To calculate the PSRR for a given RLOAD, such that the units of PSRR are converted from A/V to V/V, adjust the curve in Figure 41 by the scaling factor 20 × log(RLOAD). For instance, if RLOAD is 50 Ω, the PSRR is reduced by 34 dB (that is, the PSRR of the DAC at 250 kHz, which is 85 dB in Figure 41, becomes 51 dB VOUT/VIN). AD9709 APPLICATIONS and phase between the two baseband channels. A quadrature mixer modulates the I and Q components with the in-phase and quadrature carrier frequencies and then sums the two outputs to provide the QAM signal. QAM is one of the most widely used digital modulation schemes in digital communications systems. This modulation technique can be found in FDM as well as spread spectrum (that is, CDMA) based systems. A QAM signal is a carrier frequency that is modulated in both amplitude (that is, AM modulation) and phase (that is, PM modulation). It can be generated by independently modulating two carriers of identical frequency but with a 90° phase difference. This results in an in-phase (I) carrier component and a quadrature (Q) carrier component at a 90° phase shift with respect to the I component. The I and Q components are then summed to provide a QAM signal at the specified carrier frequency. 8 DAC DSP OR ASIC 0° CARRIER FREQUENCY 8 90° TO MIXER Σ DAC NYQUIST FILTERS 00606-044 QUADRATURE AMPLITUDE MODULATION (QAM) USING THE AD9709 QUADRATURE MODULATOR Figure 43. Typical Analog QAM Architecture In this implementation, it is much more difficult to maintain proper gain and phase matching between the I and Q channels. The circuit implementation shown in Figure 44 helps improve the matching between the I and Q channels, and it shows a path for upconversion using the AD8346 quadrature modulator. The AD9709 provides both I and Q DACs with a common reference that will improve the gain matching and stability. RCAL can be used to compensate for any mismatch in gain between the two channels. The mismatch may be attributed to the mismatch between RSET1 and RSET2, the effective load resistance of each channel, and/or the voltage offset of the control amplifier in each DAC. The differential voltage outputs of both DACs in the AD9709 are fed into the respective differential inputs of the AD8346 via matching networks. A common and traditional implementation of a QAM modulator is shown in Figure 43. The modulation is performed in the analog domain in which two DACs are used to generate the baseband I and Q components. Each component is then typically applied to a Nyquist filter before being applied to a quadrature mixer. The matching Nyquist filters shape and limit each component’s spectral envelope while minimizing intersymbol interference. The DAC is typically updated at the QAM symbol rate, or at a multiple of the QAM symbol rate if an interpolating filter precedes the DAC. The use of an interpolating filter typically eases the implementation and complexity of the analog filter, which can be a significant contributor to mismatches in gain www.BDTIC.com/ADI AVDD ROHDE & SCHWARZ FSEA30B OR EQUIVALENT SPECTRUM ANALYZER 0.1µF ACOM AVDD PORT Q CLK1/IQCLK RL LA IOUTA I DAC LATCH I DAC CB CA RL LA IOUTA RL LA RL Q DAC CA IOUTB WRT2/IQSEL LA RA BBIP VOUT RB RA 256Ω 22nF MODE FSADJ1 256Ω 2kΩ 20kΩ 22nF FSADJ2 2kΩ 20kΩ NOTES 1. DAC FULL-SCALE OUTPUT CURRENT = IOUTFS. 2. RA, RB, AND RL ARE THIN FILM RESISTOR NETWORKS WITH 0.1% MATCHING, 1% ACCURACY AVAILABLE FROM OHMTEK ORNXXXXD SERIES OR EQUIVALENT. + BBQP RB RB LOIP RA PHASE SPLITTER LOIN CFILTER BBQN RL VDIFF = 1.82V p-p SLEEP VPBF RL CB RL RA RB BBIN IOUTB AD9709 Q DAC LATCH RL DIFFERENTIAL RLC FILTER RL = 200Ω 0.1µF RA = 2500Ω RB = 500Ω RP = 200Ω CA = 280pF CB = 45pF LA = 10µH IOUTFS = 11mA AVDD = 5.0V VCM = 1.2V AD8346 REFIO ROHDE & SCHWARZ SIGNAL GENERATOR AVDD AD976x RB 0 TO IOUTFS Figure 44. Baseband QAM Implementation Using an AD9709 and AD8346 Rev. A | Page 22 of 32 RL VDAC RA AD8346 VMOD 00606-045 WRT1/IQWRT DIGITAL INTERFACE TEKTRONIX AWG2021 WITH OPTION 4 PORT I DCOM1/ DVDD1/ DCOM2 DVDD2 AD9709 out-of-band is often referred to as adjacent channel power (ACP). This is a regulatory issue due to the possibility of interference with other signals being transmitted by air. Regulatory bodies define a spectral mask outside of the transmit band, and the ACP must fall under this mask. If distortion in the transmit path causes the ACP to be above the spectral mask, filtering or different component selection is needed to meet the mask requirements. Figure 45 displays the results of using the application circuit shown in Figure 44 to reconstruct a wideband CDMA (W-CDMA) test vector using a bandwidth of 8 MHz that is centered at 2.4 GHz and sampled at 65 MHz. The IF frequency at the DAC output is 15.625 MHz. The adjacent channel power ratio (ACPR) for the given test vector is measured at greater than 54 dB. CDMA –30 Code division multiple access (CDMA) is an air transmit/receive scheme where the signal in the transmit path is modulated with a pseudorandom digital code (sometimes referred to as the spreading code). The effect of this is to spread the transmitted signal across a wide spectrum. Similar to a discrete multitone (DMT) waveform, a CDMA waveform containing multiple subscribers can be characterized as having a high peak to average ratio (that is, crest factor), thus demanding highly linear components in the transmit signal path. The bandwidth of the spectrum is defined by the CDMA standard being used, and in operation it is implemented by using a spreading code with particular characteristics. –40 –50 –60 == (dB) –70 –80 –90 –100 –110 c11 c11 cu1 –120 www.BDTIC.com/ADI Distortion in the transmit path can lead to power being transmitted out of the defined band. The ratio of power transmitted in-band to Rev. A | Page 23 of 32 C0 –130 CENTER 2.4GHz 3MHz FREQUENCY cu1 C0 SPAN 30MHz Figure 45. CDMA Signal, 8 MHz Chip Rate Sampled at 65 MSPS, Recreated at 2.4 GHz, Adjacent Channel Power > 54 dB 00606-046 I and Q digital data can be fed into the AD9709 in two ways. In dual port mode, the digital I information drives one input port, and the digital Q information drives the other input port. If no interpolation filter precedes the DAC, the symbol rate is the rate at which the system clock drives the CLK and WRT pins on the AD9709. In interleaved mode, the digital input stream at Port 1 contains the I and the Q information in alternating digital words. Using IQSEL and IQRESET, the AD9709 can be synchronized to the I and Q data streams. The internal timing of the AD9709 routes the selected I and Q data to the correct DAC output. In interleaved mode, if no interpolation filter precedes the AD9709, the symbol rate is half that of the system clock driving the digital data stream and the IQWRT and IQCLK pins on the AD9709. AD9709 EVALUATION BOARD transformer coupled, resistor terminated, and single-ended and differential outputs. The digital inputs can be used in dual port or interleaved mode and are designed to be driven from various word generators, with the on-board option to add a resistor network for proper load termination. When operating the AD9709, best performance is obtained when running the digital supply (DVDD1/DVDD2) at 3.3 V and the analog supply (AVDD) at 5 V. GENERAL DESCRIPTION The AD9709-EB is an evaluation board for the AD9709 8-bit dual DAC. Careful attention to layout and circuit design, combined with a prototyping area, allow the user to easily and effectively evaluate the AD9709 in any application where high resolution, high speed conversion is required. This board allows the user flexibility to operate the AD9709 in various configurations. Possible output configurations include SCHEMATICS DVDDIN B3 L1 DVDD BEAD BAN-JACK AVDDIN 1 C9 10µF 2 25V B2 BLK TP37 BAN-JACK BLK TP38 BAN-JACK BLK TP39 TP43 BLK DVDD L2 AVDD BEAD 1 B4 C10 10µF 25V 2 BLK TP40 BAN-JACK DGND WHT TP29 2 1 3 A B JP16 JP5 A 2B 2 2 1 DVDD WHT TP31 JP4 A 2B 1 I DGND; 3, 4, 5 WHT TP32 1 DGND; 3, 4, 5 1 2 1 R1 50Ω 2 1 R2 50Ω 2 R3 50Ω 1 2 JP1 I J 1 AGND 10 U1 Q 5 11 13 CLK 2 DVDD K CLR 15 3 C JP3 A2 B C8 0.01µF 3 PRE 3 C I 2 A B JP2 3 1 C7 0.1µF PRE www.BDTIC.com/ADI 1 DGND; 3, 4, 5 WRT2 S4 IQSEL 1 4 WHT TP30 CLK2 S3 RESET BLK TP42 JP6 DCLKIN2 DGND; 3, 4, 5 CLK1 S2 IQCLK BLK TP41 TP44 BLK JP9 DCLKIN1 WRT1 S1 IQWRT RED TP11 Q 6 12 J 9 Q U2 CLK 7 Q K CLR 74HC112 14 DGND; 8 DVDD; 16 74HC112 DGND; 8 DVDD; 16 A B DVDD 1 3 2 JP7 /2 CLOCK DIVIDER 3 WRT1 C R4 50Ω CLK1 CLK2 WHT TP33 WRT2 SLEEP 1 2 SLEEP R13 50Ω RP16 R1 22Ω RCOM 1 2 INP1 R2 22Ω 3 INP2 R3 22Ω 4 INP3 R4 22Ω 5 INP4 R5 22Ω 6 R6 22Ω 7 INP5 INP6 R7 22Ω 8 INP7 R8 22Ω 9 R9 22Ω RP9 R1 22Ω RCOM 10 1 INP8 2 R2 22Ω 3 R3 22Ω 4 R4 22Ω 5 R5 22Ω 6 R6 22Ω 7 R7 22Ω 8 INP9 INP10 INP11 INP12 INP13 INP14 R8 22Ω 9 R1 22Ω 1 2 R2 22Ω 3 R3 22Ω 4 R4 22Ω 5 R5 22Ω 6 R6 22Ω 7 R7 22Ω 8 R8 22Ω 9 R9 22Ω 10 10 INCK1 RP10 RCOM R9 22Ω RP15 R1 22Ω RCOM 1 INP23 INP24 INP25 INP26 INP27 INP28 INP29 INP30 2 R2 22Ω 3 R3 22Ω 4 R4 22Ω 5 R5 22Ω 6 R6 22Ω 7 INP31 INP32 INP33 INP34 INP35 INP36 Figure 46. Power Decoupling and Clocks on AD9709 Evaluation Board Rev. A | Page 24 of 32 R7 22Ω 8 R8 22Ω 9 INCK2 R9 22Ω 10 00606-047 RED TP10 B1 AD9709 RP3 RP1 RCOM R1 R9 22Ω P1 P1 1 4 P1 P1 3 6 P1 P1 5 8 P1 P1 7 10 P1 P1 9 12 P1 P1 11 14 P1 P1 13 16 P1 P1 15 18 P1 P1 17 20 P1 P1 19 22 P1 P1 21 24 P1 P1 23 26 P1 P1 25 28 P1 P1 27 30 P1 P1 29 32 P1 P1 31 34 P1 P1 33 36 P1 P1 35 38 P1 P1 37 40 P1 P1 39 INP2 INP3 INP4 INP5 INP6 INP7 INP8 INP9 INP10 INP11 INP12 INP13 INP14 1 16 RP5, 10Ω 3 14 RP5, 10Ω 5 12 RP5, 10Ω 7 10 RP6, 10Ω 1 16 RP6, 10Ω 3 14 RP6, 10Ω 5 12 2 DUTP2 15 DUTP3 RP5, 10Ω 4 DUTP4 13 DUTP5 RP5, 10Ω 6 DUTP6 11 DUTP7 RP5, 10Ω 8 DUTP8 9 DUTP9 RP6, 10Ω 2 DUTP10 15 DUTP11 RP6, 10Ω 4 DUTP12 13 DUTP13 RP6, 10Ω DUTP14 11 RP6, 10Ω INCK1 8 DCLKIN1 9 RP2 R9 P2 1 P2 3 6 P2 P2 5 8 P2 P2 7 10 P2 P2 9 12 P2 P2 11 14 P2 P2 13 16 P2 P2 15 18 P2 P2 17 20 P2 P2 19 22 P2 P2 21 24 P2 P2 23 26 P2 P2 25 28 P2 P2 27 30 P2 P2 29 32 P2 P2 31 34 P2 P2 33 36 P2 P2 35 38 P2 P2 37 40 P2 P2 39 INP24 INP25 INP26 INP27 INP28 INP29 INP30 INP31 INP32 INP33 INP34 INP35 INP36 RP12 RCOM R1 22Ω 1 16 RP7, 10Ω 3 14 RP7, 10Ω 5 12 RP7, 10Ω 7 10 RP8, 10Ω 1 16 RP8, 10Ω 3 14 RP8, 10Ω 5 12 2 3 4 5 6 7 8 9 10 DVDD RP7, 10Ω R9 33Ω 1 2 3 4 5 6 7 8 9 10 1 2 15 DUTP30 9 DUTP31 DUTP32 15 DUTP33 DUTP34 13 DUTP35 RP8, 10Ω DUTP36 11 RP8, 10Ω 8 DUTP24 DUTP29 RP8, 10Ω 4 DUTP23 DUTP28 RP8, 10Ω 2 2 3 4 5 6 7 8 9 10 DUTP27 11 RP7, 10Ω 8 1 DUTP26 13 RP7, 10Ω 6 R9 33Ω DUTP25 RP7, 10Ω 4 2 3 4 5 6 7 8 9 10 RCOM R1 DVDD RP7, 10Ω 6 INCK2 R9 www.BDTIC.com/ADI 1 P2 RP14 RCOM R1 22Ω P2 2 3 4 5 6 7 8 9 10 1 DUTP1 RCOM R1 4 2 3 4 5 6 7 8 9 10 1 R9 33Ω DVDD RP4 2 RCOM R1 RP5, 10Ω 6 INP23 R9 33Ω 2 3 4 5 6 7 8 9 10 1 RP11 RCOM R1 DCLKIN2 9 SPARES RP5, 10Ω 7 10 RP8, 10Ω 7 10 Figure 47. Digital Input Signal Conditioning Rev. A | Page 25 of 32 00606-048 2 DVDD RP5, 10Ω R9 22Ω 2 3 4 5 6 7 8 9 10 1 INP1 RP13 RCOM R1 AD9709 BL1 TP34 WHT 1 C1 2 VAL 1 C2 2 0.01µF ACOM JP15 DVDD C3 0.1µF 2 AVDD 1 2 1 NC = 5 3 2 R11 VAL 3 A B 1 DUTP1 1 DB7P1 (MSB) MODE 48 DUTP2 2 DB6P1 AVDD 47 DUTP3 3 DB5P1 IOUTA1 46 DUTP4 4 DB4P1 IOUTB1 45 DUTP5 5 DB3P1 DUTP6 6 DB2P1 REFIO 43 DUTP7 7 DB1P1 GAINCTRL 42 DUTP8 DUTP9 DUTP10 2 1:1 DB0P1 9 NC IOUTB2 40 10 NC IOUTA2 39 6 BL2 3 A B 1 2 C4 2 10pF 1 2 R6 50Ω C5 2 10pF 1 TP45 WHT R9 1.92kΩ 1 1 2 C17 22nF 1 2 R10 1.92kΩ C15 2 11 NC DUTP12 12 NC SLEEP 37 DUTP13 13 NC NC 36 DUTP36 DUTP14 14 NC NC 35 DUTP35 15 DCOM1 NC 34 DUTP34 16 DVDD1 NC 33 DUTP33 17 WRT1/IQWRT NC 32 DUTP32 ACOM 38 SLEEP CLK1 18 CLK1/IQCLK NC 31 DUTP31 CLK2 19 CLK2/IQRESET DB0P2 30 DUTP30 WRT2 20 WRT2/IQSEL DB1P2 29 DUTP29 21 DCOM2 DB2P2 28 DUTP28 DB3P2 27 DUTP27 22 DVDD2 1 C16 22nF DUTP11 WRT1 R5 50Ω FSADJ2 41 U2 S6 OUT1 T1 FSADJ1 44 8 AGND; 3, 4, 5 1 MODE JP8 DVDD 4 1 C6 2 10pF 1 10pF 1 1 2 R7 50Ω 1 2 R8 50Ω 2 R15 256Ω 1 REFIO TP36 WHT 2 R14 256Ω 1 1 C14 2 0.1µF 2 JP10 2 WHT TP46 BL3 TP35 WHT 3 R12 VAL 2 NC = 5 4 AGND; 3, 4, 5 1:1 1 S11 OUT2 6 T2 www.BDTIC.com/ADI DUTP23 23 DB7P2 (MSB) DB4P2 26 DUTP26 DUTP24 24 DB6P2 DB5P2 25 DUTP25 BL4 AVDD C11 2 1µF 1 C12 2 0.01µF 1 C13 2 0.1µF NC = NO CONNECT Figure 48. AD9709 and Output Signal Conditioning Rev. A | Page 26 of 32 00606-049 1 AD9709 www.BDTIC.com/ADI 00606-050 EVALUATION BOARD LAYOUT 00606-051 Figure 49. Assembly, Top Side Figure 50. Assembly, Bottom Side Rev. A | Page 27 of 32 www.BDTIC.com/ADI 00606-052 AD9709 00606-053 Figure 51. Layer 1, Top Side Figure 52. Layer 2, Ground Plane Rev. A | Page 28 of 32 www.BDTIC.com/ADI 00606-054 AD9709 00606-055 Figure 53. Layer 3, Power Plane Figure 54. Layer 4, Bottom Side Rev. A | Page 29 of 32 AD9709 OUTLINE DIMENSIONS 9.20 9.00 SQ 8.80 1.60 MAX 37 48 36 1 PIN 1 0.15 0.05 7.20 7.00 SQ 6.80 TOP VIEW 1.45 1.40 1.35 0.20 0.09 7° 3.5° 0° 0.08 COPLANARITY SEATING PLANE VIEW A (PINS DOWN) 25 12 13 VIEW A 0.50 BSC LEAD PITCH 24 0.27 0.22 0.17 ROTATED 90° CCW COMPLIANT TO JEDEC STANDARDS MS-026-BBC 051706-A 0.75 0.60 0.45 Figure 55. 48-Lead Low Profile Quad Flat Package [LQFP] (ST-48) Dimensions shown in millimeters ORDERING GUIDE Model AD9709AST AD9709ASTRL AD9709ASTZ 1 AD9709ASTZRL1 AD9709-EB 1 Z = RoHS Compliant Part. Temperature Range –40°C to +85°C –40°C to +85°C –40°C to +85°C –40°C to +85°C Package Description 48-Lead Low Profile Quad Flat Package [LQFP] 48-Lead Low Profile Quad Flat Package [LQFP] 48-Lead Low Profile Quad Flat Package [LQFP] 48-Lead Low Profile Quad Flat Package [LQFP] Evaluation Board www.BDTIC.com/ADI Rev. A | Page 30 of 32 Package Option ST-48 ST-48 ST-48 ST-48 AD9709 NOTES www.BDTIC.com/ADI Rev. A | Page 31 of 32 AD9709 NOTES www.BDTIC.com/ADI ©2000–2008 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D00606-0-1/08(A) Rev. A | Page 32 of 32