The AD9761 is a complete dual channel, high speed, 10-bit CMOS DAC. The AD9761 has been developed specifically for use in wide bandwidth communication applications (e.g., spread spectrum) where digital I and Q information is being processed during transmit operations. It integrates two 10-bit, 40 MSPS DACs, dual 2x interpolation filters, a voltage reference, and digital input interface circuitry. The AD9761 supports a 20 MSPS per channel input data rate that is then interpolated by 2x up to 40 MSPS before simultaneously updating each DAC.
The interleaved I and Q input data stream is presented to the digital interface circuitry, which consists of I and Q latches as well as some additional control logic. The data is de-interleaved back into its original I and Q data. An on-chip state machine ensures the proper pairing of I and Q data. The data output from each latch is then processed by a 2x digital interpolation filter that eases the reconstruction filter requirements. The interpolated output of each filter serves as the input of their respective 10-bit DAC.
The DACs utilize a segmented current source architecture combined with a proprietary switching technique to reduce glitch energy and to maximize dynamic accuracy. Each DAC provides differential current output thus supporting single-ended or differential applications. Both DACs are simultaneously updated and provide a nominal full-scale current of 10 mA. Also, the full-scale currents between each DAC are matched to within 0.07 dB (i.e., 0.75%), thus eliminating the need for additional gain calibration circuitry.
The AD9761 is manufactured on an advanced low cost CMOS process. It operates from a single supply of 2.7 V to 5.5 V and consumes 200 mW of power. To make the AD9761 complete it also offers an internal 1.20 V temperature-compensated bandgap reference.
|Title||Content Type||File Type|
|AD9761: Dual 10-Bit TxDAC+™ with 2 x Interpolation Filters Data Sheet (Rev C, 06/2003) (pdf, 969 kB)||Data Sheets|
|AN-912: Driving a Center-Tapped Transformer with a Balanced Current-Output DAC (pdf, 246 kB)||Application Notes|
|AN-237: Choosing DACs for Direct Digital Synthesis (pdf, 1156 kB)||Application Notes|
|AN-595: Understanding Pin Compatibility in the TxDAC® Line of High Speed D/A Converters (pdf, 36 kB)||Application Notes|
|AN-302: 02: Exploit Digital Advantages in an SSB Receiver (pdf, 417 kB)||Application Notes|
|Digital to Analog Converters ICs Solutions Bulletin (pdf)||Solutions Bulletins|
|RAQs index||Rarely Asked Questions||HTML|
|Glossary of EE Terms||Glossary||HTML|
|Title||Content Type||File Type|
DAC Harmonic Analyzer
This tool displays harmonic images and spurs in a DAC output. The user can define a post-DAC analog filter to suppress these images. The effect of this filter is plotted on the graph and shown in the accompanying chart.
|DAC Harmonic Analyzer||HTML|
|AD9761 IBIS Models||IBIS Models||HTML|
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