Design of a Wideband and Low Phase Noise CMOS LC VCO

A wideband CMOS LC VCO is designed.Based on the analysis of the sources of the VCO phase noise,the structure of VCO is optimized and the technique of noise filtering is used,the switching capacitance arrays are exploited to expand the bandwidth.The VCO is fabricated in 0.18 μm CMOS RF process,the chip area is 0.4 mm×1 mm.Measurements show:the operating frequency covers 3.34～4.17 GHz,when the central frequency is 4.02 GHz,the phase noise is-120 dBc/Hz at 1 MHz offset while dissipating 10 mW from 1.8 V supply.