I guess it's because you increase the bias current so as to push the tail in triode....
Generally, more power, less noise.
So you should compare the results with the same power consumption.
AZADBAKHT wrote on Jan 20th, 2015, 11:36am:Hi all,
I designed a LC-VCO for tuning range of 4.8 to 5.8 GHz.
when i do sweep PSS & PNoise analysis for give best Phase Noise, when I-Tail is teriod region(M4 in picture), Phase Noise of VCO is the best more then Saturation region.e
can anyone tell me why?
Best of Regards,
Azadbakht.