Is the PLL figure of merit (FOM) referenced to the output phase detector charge pump or the input to the phase detector? Does the FOM value also include both the reference divider noise and feedback divider noise?
The FOM in our PLL datasheets is the Normalized Phase Noise Floor of the PLL chip (reference path + phase detector + N divider + charge pump). By PLL chip, I mean the actual ADF4xxx product (assuming it's a discrete solution).
The Normalized Phase Noise Floor is measured by locking the PLL in a closed loop with a very wide loop bandwidth (LBW). The wide LBW ensures the pure phase noise contribution of the PLL chip is dominant. You can see this in ADIsimPLL if you increase the LBW and look at the Chip phase noise trace in the Phase Noise plot on the FreqDomain tab.
More information: https://ez.analog.com/docs/DOC-1842
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