AD9834: MSB output jitter reduction

Document created by analog-archivist Employee on Feb 23, 2016Last modified by analog-archivist Employee on Feb 23, 2016
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We would like to get a output square wave by using of AD9834.
The MSB is output at pin 16 but the edge is jittering and the waveforms have
been attached.
As we know, the jitter of output is dominated by that of MCLK, but the problem
is still exists when the jitter of MCLK is less. Could you please tell us how
to decrease the jitter and what performance we can achieve?

 

We did some analysis on this with the AD9834 and a 5th order elliptic filter.
We filtered the Iout signal and fed it back into the Vin pin. The Comparator
was enabled and fed back out on the Sign Bit Out pin.
The jitter reduce from the inverse of the MCLK (13nS) to ~600pS. Further
filtering would improve this.
This was for a 10MHz signal with a 40MHz LP filter – so if we moved the corner
frequency down to say 12 MHz we would achieve better jitter still.

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