VCO: corner frequency vs cut-off corner frequency

[casual]

when we say "flicker corner freq of a vco output phase noise", does it refer to the slope of 1/f^3 or the boundary between 1/f^3 and 1/f^2 (cutoff corner freq, i think). It does cause me confusion.

wiki: corner freq = cutoff freq

when the simulated pnoise (spectreRF) freq waveform labels the "CorFreq: PN-3dB=5k -50" (dBc/Hz). Does it mean the cutoff corner freq is 5kHz? I think it only shows the slope of 1/f^3 rather than the cutoff corner freq. Because from the waveform, the -20dBc & -30dBc slope are intersect at much high freq than 5kHz.

 

[vfone]

One way to estimate the phase noise meaning function of the SSB slope, is the below approximation:
- 1/f^3 is 30dB/octave
- 1/f^2 is 20dB/octave
- 1/f is 9dB/octave
- Leeson's equation apply where the slope is 6dB/octave
- fo/(2*QL) the corner between phase noise slope and the "flat" phase noise

Generally is difficult for any simulator software to predict the flicker noise if doesn't have an accurate silicon model.