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Yet another AD9122 clocking question...

Question asked by jeffkt2 on Mar 19, 2015
Latest reply on Mar 27, 2015 by rejeesh



I'm working with a Zedboard + FMCOMMS1 and the no-os reference design. From what I understand, the AD9122 DAC sample rate is set to 491.52 MHz and 1x interpolation. This would require one Q sample and one I sample to be delivered every 1/481.52e6 seconds.

In the word interface mode described by the AD9122 data sheet, the IQ samples are interwoven and clocked in by DCI, and I would expect DCI to also have a clock rate of 491.52 MHz. When I probe the signals, I see DCI at half that rate (256.76 MHz). Is this correct, or am I missing something fundamental?