Phase noise analysis and design of a 3-GHz bipolar differential colpitts VCO

Abstract

This paper presents a low-phase-noise differential bipolar Colpitts VCO, implemented in a 0.35/spl mu/m BiCMOS process. A time-variant phase noise analysis yields closed- form symbolic expressions for the dominant noise sources in the 1/f/sup 2/ phase-noise region. Measurements show a phase noise of -123 dBc/Hz at 1MHz offset from a 2.8-3.1 GHz carrier, for a figure-of-merit of 183 dBc/Hz. A very good agreement between the derived theoretical formulas, spectreRF simulations, and measurements is observed.