A quadrature voltage-controlled oscillator using phase-adjusting architecture for suppressing phase noise

Abstract

A low-phase-noise 25-GHz quadrature voltage-controlled oscillator (VCO) using 180-nm TSMC CMOS is presented. To equalize the oscillation frequency to the LC-resonant frequency, a phase shifter at a transistor gate adjusts a phase delay due to an RC delay in a transistor. This phase-adjusting architecture extends operation bias range and suppresses phase noise by 6 to 9 dB compared with a conventional differential VCO.