Ths is comment on recent posting of an App Note
Achieving phase coherence between multiple Fractional-N PLLs ADF4350 Phase Resync and Phase Programmability
Achieving phase coherence between multiple Fractional-N PLLs
ADF4350 Phase Resync and Phase Programmability
Please post the two references cited as hyperlinks - 'here' - I could not click into them.
Does the resync feature in the ADF4350 or ADF43511 apply to the internal VCO output divider (/2/4/8..//64) that extends the VCO output to < 140MHz? Because the bock diagram on page 1 of the data sheet implies the VCO o/put divider is seperate from the N/N+1 prescalar and other counters in the PLL feedback. This would mean the VCOs in differrent PLLs were re-synced, but not the final outputs.
PS: for integer-N phase coherency, I expect it is sufficient to sync the internal Ref divders at initalization. No further action is needed when re-tuning.