AnsweredAssumed Answered

AD9788 DATACLK delay causes noise spur in output

Question asked by Naji on Oct 16, 2012
Latest reply on Nov 2, 2012 by YiZ

Running the AD9788 at 714.42 MHz with x4 Interpolation giving a DATACLK frequency of 178.605 MHz. DATACLK needs to be delayed for proper data alignment. As soon as the delay is enabled, whether in Auto or Manual mode, a noise spur shows up at (178.605 - Fout) where Fout in this case is 98.5 MHz.

 

Why is the delay circuit creating the noise?

 

How can I overcome it?

 

Thank you

Outcomes