ADF4360-7: ADIsimPLL gets small L value

Document created by analog-archivist Employee on Feb 23, 2016Last modified by analog-archivist Employee on Aug 10, 2016
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I have a question about ADIsimPLL for simulating ADF4360-7. When I am setting
the output as a fixed frequency of 818.4MHz, PFD=2.5575, the external inductor
L1=L2=611pH.
But we can not get such parameters according to the equation or figure 24 on
page 22 of datasheet. It seems L1, L2 should be at least higher than 1nH. Would
you advise please?

 

611pH is hard to implement in real coil inductors, but the ADIsimPLL software
could still calculate the value.
The problem is because you select the div/2 output which means the VCO is
actually run @1.6GHz.
You can change the VCO frequency to 818.4MHz and this will result in a higher
inductor value( see  picture).

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