Hi all,

I have designed a wide-range LC VCO, and I am running PSS/Pnoise for checking the phase noise of the VCO. I got suspicious about the results when I found that the phase noise started changing with tstab for a range of oscillation frequencies (For example, a tstab of 500n is giving me a phase noise of -101.8 dBc/Hz @ 1MHz while a tstab of 5u is giving me a phase noise of -108 dBc/Hz @1MHz!) Could you please help me out in figuring out whether the Pss/Pnoise results are proper or not? Is that something to do with the tolerance limit (it's the default value by the way)? How can I confirm if the results of pss/pnoise are correct? This is holding up my project, as I am not able to meet the required phase noise specs. I am also looking for resources to understand pss/pnoise functioning.

Also I had one more question. Is it possible to get different frequencies (an error of 3% to 4%) in transient simulation and pss?

Thanks!