supermoment
|
I try to design a typical cmos LC VCO. I found out the phase noise degrades a lot after adding nmos varactor as compared to ideal cap.
The phase noise could be improve if add a bypass capacitor (for ac ground) however it will add additional load to the LC tank results in narrow tuning range. Is it common to do so in real practice??
I try to improve it by adding more fingers of nmos varactors. It helps a bit only.
Is there any way to improve the varactor?
|