Your question is not "RF Measurement".
You don't seem to understand a definition of loaded Q of LC VCO.
analog_cha wrote on Jan 30th, 2009, 5:07am:Say,i am using an inductor of tsmc18rf in the LCVCO design. I choose some value for the inductance while instantiating it.
Did you confirm inductance value by AC or SP analysis ?
I think you just believe inductance value in setting parameter of inductor component provided in tsmc18rf PDK without confirming its value by AC(SP) analysis.
http://www.designers-guide.org/Forum/YaBB.pl?num=1205240723/9#9analog_cha wrote on Jan 30th, 2009, 5:07am:But after doing dc simulation and seeing the operating point of the inductor, the inductance value is different. Is it because of loading??
I don't think so.
Generally inductor model is composed of multiple L, R and C.
http://www.designers-guide.org/Forum/YaBB.pl?num=1205764700What value is showed as the operating point of the inductor in tsmc18rf PDK ?
And what value is used as parameter of inductance of PDK ?
You have to consider these issues.
Do you think such inductance value by DC analysis is meaningful for VCO design ?
analog_cha wrote on Jan 30th, 2009, 5:07am:And also i would like to know the quality factor of the inductor after being kept in the LCVCO.
Loaded Q of oscillator is calculated from phase noise plot.
QL=f0/(2*fa), where f0 is oscillation frequency and fa is coner frequency of -6dB/oct and floor noise.
See page.4 of the following.
http://www.zen118213.zen.co.uk/Systems_And_Devices_Files/PhaseNoise.pdf