Hello，these days I met a phase coherent problem with two AD9164.
Both two AD9164 use the same DAC CLK, and I config them work in NCO only mode, the output signal can phase coherent.
Change the NCO FTW, and use TX_ENABLE load FTW，also the output signal delay is fixed.
1，When I reset these AD9164 use a external signal, and then config two AD9164 work in NCO only mode. The output signal delay is changed.
2，Not reset these AD9164, only switch the DAC CLK, it also change the output signal delay.
How can I solve this phase coherent problem.
The output signal delay changes from POR to POR (or by changing the clock) because of the internal divide-by-4 clock. Sorry we can't help much here.
When you are talking about switching the FTW frequency, is this happening by using FFH registers (32bit NCOs) or FTW of the main NCO (48bit NCO)? if it is done by just switching FTW of the main NCO, it doesn't support any mode other than Discontinuous Phase mode. You should use FFH registers to be able to use phase coherent mode while hopping between different FFH registers.
I just use the main 48bit NCO to switch frequency, and control TX_ENABlE to load new FTW.