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synchronizing multiple AD9739

Question asked by timothy.starr on Jan 18, 2012
Latest reply on Jan 25, 2012 by danf

Hello-

 

I would like to synchronize 4 AD9739 DACs, but they are on different boards.  I know the preferred method for syncing the DACs is to use the sync_out signal from the master DAC and fanout the signal to the rest of the DACs.  I also noticed in the datasheet that the skew between the DAC clock and the sync_in signal must be less than 200 ps which I doubt I would be able to achieve since the DACs are separated by several inches.The clock frequency is 1.8GHz  I have the ability to phase shift the DAC clock going to each board so that each DAC will see the clock at the same time, using HMC934 phase shifterafter a 1:4 splitter.

 

I think the problem is that since the clock is arriving at each DAC board at the same time, the time it would take for the sync signal from the master DAC to reach the other DACs, the skew between the sync signal and the DAC clock would most likely be greater than the 200ps requirement.  Would it be possible to add delay to each of the sync_in signals from the master DAC to individually align the sync_in signal at each DAC (according to the datasheet, the sync_in signal should be set exactly between Phase 0 and Phase 1 of the DAC clock)? If so, how?

 

Do you have any advice on the best topology to connect the DACs to take advantage of the synchronization controller?

Thanks and Best Regards,

 

-Tim Starr on behalf of RS@MI

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