Wide tuning range inversion-mode gated varactor and its application on a 2-GHz VCO

This paper presents a novel inversion-mode three-terminal varactor with a capacitance ranging from 0.7 pF to 2.3 pF, achieving a /spl plusmn/53% variation in the capacitance. The new device is implemented in a 0.35-/spl mu/m standard CMOS process. The measured quality factor is 22 at 2 GHz. A 2-GHz VCO is designed with this new varactor and is able to achieve a tuning range of 320 MHz with a maximum tuning gain of 220 MHz/V.