ADF4107: Phase noise

Document created by analog-archivist Employee on Feb 23, 2016Last modified by rbrennan on Mar 14, 2016
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Q

Do you have information on the phase noise of the dividers used in your current
frequency synthesiser devices ?
You publish total device phase noise performance, which is usually adequate,
but I want to use the ADF4107 as a programmable divider, and I'm not able to
model the system properly...

 

A

We have not evaluated the counters and charge pump separately.
However, we do know that the CP is not a significant contributor to phase
noise.
We have deduced this by virtue of the fact that changing the CP current from
5mA to 625µA makes no difference to the overall phase noise. 
In theory, the best phase noise is achieved with max CP current.

 

Therefore, it is safe to assume that the PN achieved when used as a counter
will be much the same as the phase noise quoted in the data sheet.

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