BackerShu wrote on Nov 19th, 2011, 4:28pm:Thanks, YCY!
Some more confusions.
By real phase noise, I mean the measurement results. So to your understand, this should be the same with the phase noise simulation, if I chose SSB option.
Here comes the parts I am confusing.
Confusion 1: What should be the physical meaning of phase noise? is it SSB phase noise or DSB phase noise?
Confusion 2: As stated by RFDUDE, in the mixer simulation, the SSB option would cause 3dB difference with measurement result. So, it comes that in VCO simulation, the result get when SSB option is set is equal to the measurement result, while it's not true with Mixer. Is this really the case in Cadence? I have doubt about this.
Physical meaning of phase noise is the PSD of phase error,
which will be the same for both upper and lower sideband.
SSB phase noise indicates only one sideband is considered,
while DSB phase noise includes both upper and lower sideband,
thus it will be 3dB higher than SSB phase noise.
So, for what you have asked in the beginning of this thread,
SSB phase noise means half DSB phase noise.
When we measure or calculate phase noise of a VCO, SSB phase noise is always used.