An improved dual-conduction class-C VCO using a tail resistor

This paper proposes a method to improve the power consumption of dual-conduction class-C VCO. The dual-conduction class-C VCO has two pairs of cross-coupled transistors for low supply voltage operation. One is a main pair for the class-C operation, the other is an auxiliary pair for startup. The auxiliary pair continues to operate after the VCO starts class-C operation, which consumes additional power. Thus, we added a resistor to the source node of the auxiliary pair. Since the resistor reduces the current of the auxiliary pair, the power consumption can be improved. The proposed VCO is fabricated by using a 0.18 μm CMOS technology. It oscillates at 5.4 GHz with 0.20V supply voltage, consumes 96μW, and achieves a FoM of -187 dBc/Hz.