I am designing an LC based voltage control oscillator. I want to simulate phase noise of my oscillator, but, I ALWAYS got a very bad phase noise performance (for example, -60 dBc/Hz @ 1 MHz offset, compared to my expectation -110 dBc/Hz). The reason is that in the periodic steady state analysis (PSS), the fundamental frequency is simulated wrong. I estimate the fundamental frequency is 5 GHz from the transient waveform, whilst the fundamental frequency given by PSS simulation is 2.5 GHz. Has anyone encountered or does anyone have any knowledge of this problem?

I figure out a method to get around this half harmonic frequency problem. In the pnoise analysis, people usually choose “sweep type” as “relative”, and “relative harmonic” as 1. I wonder if I can choose “relative harmonic” as 2 to compensate the half harmonic in PSS simulation.

Thank you.