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ADF4350 Phase Resync

Question asked by DRS-des on Oct 8, 2012
Latest reply on Oct 9, 2012 by icollins

Ths is comment on recent posting of an App Note

 

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.

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