Dear All,

Today I used Pnoise to simulate the current noise of a PFD+Charge_Pump.

The setting for pnoise is:
pnoise pnoise sweeptype=absolute start=10 stop=10G
+ maxsideband=50 oprobe=V1 iprobe=V2 refsideband=0
+ annotate=status

The results seems resonable. However, if I set start=0 ( I read the paper by key: Simulating Swiched-Capacitor Filterss by SpectreRF, he set start=0), the results seems abnomal. Attached please find the simulation results. The red curve corresponds start=10, the green curve corresponds start=0. Any commends are welcome.

M0 and M1 mean nothing. They are just the names of markers (the plots are produced with WaveScan, if I use AWD, they should be "A" and "B").

Ken, I need your feedback about this question. Another quick question is:
When I simulate the current noise of PFD+CP, I tie ref_clk and div_fb together (simulate the locked state), does this make sense? The sweep type of PNOISE was set to absolute, is this right?

Thanks,

Lunren