Mayank wrote on Jun 29th, 2010, 9:09pm:On the other hand, Lphi (which is a small signal approximation of phase noise b/w osc. linewidth & Fosc/2 ) can go above 0 dBc below corner freq.
But true Sphi wont.
Wrong.
I don't know what you mean by
Lphi.
But in actual Measurement using Actual Instruments, L
SSB(f)=C/N0 never go above 0dBc/Hz but S
Φ(f) can go above 0dBrad/Hz.
On the other hand, in simulation using current EDA Tool, L
SSB(f) could go above 0dBc/Hz at low offset especially in the presence of 1/f noise.
Mayank wrote on Jun 29th, 2010, 9:09pm:What i still wonder is if it's due to lack of proper gaussian flicker noise model in technology models OR is it due to simulator's inability to solve gaussian noise in low-freq. as opposed to Lorentzian after linewidth.
No.
It is simply due to a limitation of small signal analysis.
See
http://www.designers-guide.org/Forum/YaBB.pl?num=1263835149/6#6