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ADF4351 shift in output frequency

Question asked by tryinghard on Apr 24, 2013
Latest reply on May 7, 2013 by rbrennan

Hi,

 

   I'm using ADF4351 to generate following RF outputs, 57Mhz, 185Mhz, 367Mhz, 567Mhz, 1002Mhz.

 

for 57Mhz, im getting 1Mhz offset meaning 58Mhz and it is stable.

 

for other frequencies, from 185Mhz, 185Mhz, 367Mhz, 567Mhz having 5Mhz offset,

 

1002Mhz having 9Mhz offset and except 57Mhz all other frequencies were unstable meaning when i probe (high impedance probe) using Spectrum analyzer, the output starts to drifting. for example, im supposed to get 367Mhz but im getting 372Mhz and it starts to vary slowly from 372Mhz to 365Mhz and goes on like this for all other frequencies except 57Mhz. attached is my loop filter values and i simulated using ADIPLLsim tool. please any suggestions...

 

Regards

Arunprakash G

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