A Class-C LC VCO for 802.11 b/g/n and Bluetooth

This paper presents a Class-C LC VCO which can be used for 802.11 b/g/n, Bluetooth and ZigBee. Implemented in 0.18μm process, the VCO can achieve coarse frequency tuning and fine frequency tuning. The bias voltage of the cross-coupled transistors can be adjusted to control the conduction angle of the VCO to improve the current utilization efficiency. The bias current can be adjusted to achieve a compromise of power consumption and phase noise.