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Synchronizing multiple HMC7044 chips

Question asked by Johannes2 on Jun 16, 2017
Latest reply on Jun 20, 2017 by Johannes2

I am struggling to understand the HMC7044 multi-device synchronization.

 

We want to use the device to generate sample clocks for data converters with a frequency between 5MHz and 400MHz.

The reference clock is 312.5MHz, and the VCXO will probably be 100MHz (still TBD).

We have multiple identical boards, all receiving the same 312.5MHz RefClk.

 

The datasheet stays I should use the SYNC signal to synchronize multiple HMC7044 devices. The sync signal is first synchronized (sampled?) with the VCXO.

But the VCXOs on different boards can be out of phase to each other:

Timing diagram

I don't see how we can sync all the outputs of multiple boards, if the sync signal is first synchronized with the VCXO that can be on different phases.

 

Am I missing something, or is this indeed not possible?

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