A complementary Colpitts VCO implemented with ring inductor

Abstract

This paper presents a novel differential voltage controlled oscillator (VCO). The VCO uses a closed-loop ring inductor and is composed of two single-ended complementary Colpitts LC VCOs coupled by two identical inductors and is implemented in a standard 0.18 mum CMOS technology. This differential VCO operates at 5.76-6.76 GHz. The measured phase noise of the VCO operating at 6.7 GHz is -118.5 dBc/Hz at 1-MHz offset while the VCO draws 3.75 mA and 5.625 mW consumption from a supply voltage of 1.5 V.