Design and analysis of a 3.85–5.23 GHz linear-tuning CMOS LC-tank VCO

Design and analysis of a highly linear-tuning CMOS LC-tank voltage-controlled oscillator was presented in this paper. A single tuning resonant tank with a distribution MOS varactor biasing pair and the 2bits binary-weighted band-switching capacitors is proposed to reduce the variation of tuning sensitivity and cover 31% tuning range from 3.85GHz to 5.23GHz. The simulated phase noise is -115.3dBc/Hz at 1MHz offset frequency from 5.23GHz carrier. The proposed VCO core consumes 4.5mA current at 1.8V supply voltage. The whole chip area is 1.0μm × 0.95μm by using TSMC 0.18μm CMOS process.