A Low Power and Low Phase Noise Complementary Colpitts Quadrature VCO

Abstract — A low power and low-phase noise quadrature voltage controlled oscillator (QVCO) using the differential complementary Colpitts oscillator topology has been developed. A transformer inductor is used to form a differential output oscillator and the back-gate coupling technique is used to generate quadrature outputs. The advantage of proposed QVCO is analyzed in terms of power consumption, phase noise, and figure of merit. The low power QVCO has been fabricated with 0.18um CMOS technology for 4.8GHz band operation and its phase noise is-115.24 dBc/Hz at 1MHz offset while operated with 2.2mA current consumption and 3.96mW power consumption for the whole QVCO from 1.8V supply. The figure of merit is-182.2 dBc. Key Words —CMOS, Colpitts oscillator, quadrature, voltage controlled oscillator, back-gate coupling, transformer. I