A physical model of a CMOS varactor with high capacitance tuning range and its application to simulate integrated VCOs

Abstract A physical model of a novel MOS varactor design is presented. The voltage and frequency dependent results for the varactors small-signal capacitance and resistance agree well with measured values for different device geometries. The model is further tested through simulating a fully integrated voltage controlled oscillator (VCO) for UMTS applications. Measured frequency tuning and phase noise of the VCO are accurately reproduced.