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Is ADF4350 lock time dependent on values of FRAC and MOD

Question asked by Dwijen on Sep 29, 2011

Hi,

I am using ADF4350 in one of my design. As per datasheet of the ADF4350, we can synthesize any frequency by setting values of INT, FRAC and MOD.

Now

 

RFout = [INT + (FRAC/MOD)] X fpfd/RFdivider

 

From this equation it is apparent that synthesized output frequency depends upon ratio FRAC/MOD and not individual values of FRAC and MOD. Now value of MOD depends upon channel resolution we are willing to achieve.     

 

Now my question is does lock time depends on selection of values of FRAC and MOD, keeping ratio constant? I mean for example value of FRAC=1 and MOD=10 would generate same frequency as value FRAC=10 and MOD=100(keeping all other values same like INT and fpfd). Does lock time to generate same frequency in both the case would be same? (it is obvious that channel resolution would be different for both values of MOD=10 and MOD=100. We are not consedered abut channel resolution in this case)

 

Thanks & Regards,

Dwijen Pandya

RF Design Engineer,

HCL Technologies

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