Phase Noise Analysis of Bipolar Class-C VCOs With Delay in Oscillator Loop

The expression for phase noise of a bipolar class-C voltage controlled oscillator (VCO) with an ideal delay in the oscillator loop is derived in this paper. The impact of internal device parasitics is then quantified and supported with circuit simulation results. A bipolar class-C VCO is fabricated in a 130-nm BiCMOS technology to validate the analytical predictions. It exhibits a phase noise performance of -112.2 dBc/Hz at 1-MHz offset when running at 19.2 GHz. The tuning range is 7%, and the overall FoM and FoMT are 180.4 dBc/Hz and 177.3 dBc/Hz, respectively.