Thanks a lot for your advices. I have tried the settings you recommended and have some questions.
Setting the absolute stop frequency at 400MHz does not cover the beat frequency. Do you actually mean setting the range to 400M~1.2GHz? Additionally, it seems with absolute frequency setting I can plot PSD but cannot plot phase noise spectrum and related jitter. From PSD plot it seems the sweep points should be enough.
I set the frequency back to relative harmonics, and notice that when I set harmonic to 1, inverter output jitter > input jitter. But when I set harmonic to a large value (7 here), inverter output jitter < input jitter, which is confusing me. I thought for more accurate noise calculation the harmonic value should be set to high in order to include more foldered noise around high harmonics, right? Below I list the RMS single period jitters from my simulations as reference.
Harmonic=7 inverter input jitter: 325fs inverter output jitter: 14fs
Harmonic=1 inverter input jitter: 46fs inverter output jitter: 74fs
Please let me know if any ideas. I appreciate your time and help.