A Dual-Conduction Class-C VCO for a Low Supply Voltage

Abstract

This paper proposes a dual-conduction class-C VCO for ultra-low supply voltages. Two cross-coupled NMOS pairs with different bias points are employed. These NMOS pairs realize an impulse-like current waveform to improve the phase noise in the low supply conditions. The proposed VCO was implemented in a standard 0.18µm CMOS technology, which oscillates at a carrier frequency of 4.5GHz with a 0.2-V supply voltage. The measured phase noise is -104dBc/Hz@1MHz-offset with a power consumption of 114µW, and the FoM is -187dBc/Hz.