Description

The AD9761 is a complete dual channel, high speed, 10-bitCMOS DAC. The AD9761 has been developed specifically foruse in wide bandwidth communication applications (e.g., spreadspectrum) where digital I and Q information is being processedduring transmit operations. It integrates two 10-bit, 40 MSPSDACs, dual 2x interpolation filters, a voltage reference, anddigital input interface circuitry. The AD9761 supports a20 MSPS per channel input data rate that is then interpolatedby 2x up to 40 MSPS before simultaneously updating eachDAC.The interleaved I and Q input data stream is presented to thedigital interface circuitry, which consists of I and Q latches as wellas some additional control logic. The data is de-interleaved backinto its original I and Q data. An on-chip state machine ensures theproper pairing of I and Q data. The data output from each latch isthen processed by a 2x digital interpolation filter that eases thereconstruction filter requirements. The interpolated output of eachfilter serves as the input of their respective 10-bit DAC.The DACs utilize a segmented current source architecture combinedwith a proprietary switching technique to reduce glitchenergy and to maximize dynamic accuracy. Each DAC providesdifferential current output thus supporting single-ended ordifferential applications. Both DACs are simultaneously updatedand provide a nominal full-scale current of 10 mA. Also,the full-scale currents between each DAC are matched to within0.07 dB (i.e., 0.75%), thus eliminating the need for additionalgain calibration circuitry.The AD9761 is manufactured on an advanced low cost CMOSprocess. It operates from a single supply of 2.7 V to 5.5 V andconsumes 200 mW of power. To make the AD9761 complete italso offers an internal 1.20 V temperature-compensated bandgapreference.PRODUCT HIGHLIGHTS Dual 10-Bit, 40 MSPS DACs A pair of high performance 40 MSPS DACs optimized for low distortion performance provide for flexible transmission of I and Q information. 2x Digital Interpolation Filters Dual matching FIR interpolation filters with 62.5 dB stopband rejection precede each DAC input, thus reducing the DACs? reconstruction filter requirements. Low Power Complete CMOS dual DAC function operates on a low 200 mW on a single supply from 3 V to 5.5 V. The DAC full-scale current can be reduced for lower power operation, and a sleep mode is provided for power reduction during idle periods. On-Chip Voltage Reference The AD9761 includes a 1.20 V temperature-compensated band gap voltage reference. Single 10-Bit Digital Input Bus The AD9761 features a flexible digital interface that allows each DAC to be addressed in a variety of ways including different update rates. Small Package The AD9761 offers the complete integrated function in a compact 28-lead SSOP package. Product Family The AD9761 Dual Transmit DAC has a pair of Dual Receive ADC companion products, the AD9281 (8 bits) and AD9201 (10 bits).

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Part number: AD9761-EBZ

More details from Analog Devices Inc.