A 5.8 GHz and -192.9 dBc/Hz FoMT CMOS class-B capacitively-coupled VCO with Gm-enhancement

Abstract

This paper presents a novel gm enhancement method to minimize the oscillation start-up current in a CMOS voltage-controlled oscillator (VCO). A class-B biasing is achieved by extending the capacitive-feedback network, resulting in a larger output amplitude and hence a lower phase-noise. The flicker-noise of the tail current source is further minimized by self-biased switching current-sources. The proposed VCO is demonstrated in a 65 nm CMOS technology. The prototype measurement result shows a tuning range of 16 % with a phase-noise of −119.2dBc/Hz at 1 MHz offset from a 5.7 GHz carrier frequency. The VCO consumes only 3.6 mA from a 1.2 V supply.