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AD9548 how to generate a phase alignment clock to PPS

Question asked by Marck on Jun 29, 2012
Latest reply on Jul 25, 2012 by pkern

Hello,

 

Im using a custom board with AD9548 connected to an GPS retriever. I was able to successfully configure the device to get the 10Mhz output frequency locked to 1PPS signal(output from DDS at 80Mhz divided by 8). Now I wanted to generate 10Mhz clock phase alignment to PPS and Im a bit confused about phase alignment mechanisms in AD9548 described in datasheet.

 

As I understand the phase alignment is done by a clock distribution synchronization. When I configured active reference synchronization to frequency or phase lock I see on the oscilloscope that the output clock of AD9548 is only phase aligned for some time after the lock event. But when I select the DPLL feedback edge as a synchronization source the output clock signal seems to be phase alignment all the time with PPS.

 

Can you advise how should I configure the device and what are the differences/use cases for the two sync modes?

 

Mark

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