Design of fully-integrated 5GHz differentially-tuned CMOS LC VCO

A fully integrated 5GHz differentially-tuned CMOS PMOS-NMOS cross-coupled LC voltage controlled oscillator (VCO) is presented. To increase the linearity of the VCO tuning characteristic, an LC tank structure which has the differentially tunable series varactor combination is used in this design. The VCO is designed in a 0.18 μm standard CMOS process with a 1.8V supply. It achieves a phase noise of -113.5dBc/Hz at 1MHz offset from a carrier frequency of 5GHz and has a tuning range of 1.4SGHz (29%).