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Synchronising a pair of AD9910 evaluation boards

Question asked by GHz on Oct 25, 2011
Latest reply on Oct 27, 2011 by DSB


I have a pair of AD9910 eval boards and an ADCLK846 eval board and I would like to use them on the bench synchronised to generate an agile quadrature signal source. I have configured the master AD9910 eval board to generate the sync_o +/- signal and accept an external sync_i +/- signal. I have configured the slave for external sync_i +/- input. I have fed the ADCLK846 clock input with the master sync_o and distributed the buffered outputs back to the master and slave sync_i inputs.

I have been careful to use matched length coaxial cables and also to split the 1GHz clock between the two DDS so that they are closely phase aligned also.

Running two instances of the AD9910 application software it looks like I can synchronise the two DDS together and by varying the sync pulse delay, the phase of the two DDS output shifts as I might expect.

In order to get them phase aligned though, I think the last thing I need to do is apply a coincident io_update pulse to each DDS. CN-0121 specifies a Tek DG2020A pattern generator to do this, are there any alternative methods as I don't have access to one of these instruments please? Can I not just feed the io_update from the master to the slave with a very short lead?

Is there anything else I need to set up other than a phase offset of 90 degrees in the profiles window in order to get my setup working please?

Many thanks,