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AD9833 sin wave to square wave clock jitter

Question asked by ttse007 on Jan 17, 2017
Latest reply on Jan 30, 2017 by musach

I am trying to use the DDS to generate a square clock with jitter close to the oscillator feeding it. For tunability, I am feeding the DDS sin wave output into a comparator at zero crossing.

 

For testing, I have tried the square wave output at 2^n division frequency and got close to the jitter of my oscillator (e.g. 62.5khz and 125khz with 16MHz osc). However, at the same frequencies I didn't get nearly the same performance from the sin wave/comparator, I have read about spurs and sampling error, and have tried LPF of the sin wave. Is there anything I am missing or do I need to move to a higher resolution DDS?

 

Thanks.

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