Design of 3.7 GHz Wideband CMOS LC VCO

A 3.7 GHz wideband CMOS LCVCO was designed.Capacitance switching technique was used for compensating the variance of rocess,temperature and the supply.Some optimization designs were made with the on-chip inductor and the RF switches to get the maximum Q-value.The VCO was fabricated in Hejian 0.18 μm CMOS mixed signal process,the chip area was 0.4 mm×1 mm.Measurements show that the operating frequency covers 3.4 to 4 GHz,according to the output spectrum,the phase noise is-100 dBc/Hz@ 1 MHz offset while dissipating 10 mW from 1.8 V supply.Measure results show the VCO has a large operating range of frequency and low phase noise,it can be used in PLLs and frequency synthesizers.