A mismatch compensation circuit for CMOS quadrature VCO phase error

Abstract

This paper presents an analysis of phase errors; in LC quadrature VCO with a common-mode model. A mismatch compensation circuit is proposed to alleviate phase errors due to common-mode transconductance mismatch. With the compensation circuit, quardature phase errors and image rejection ration rate (IRR) are improved about 1.5 degrees and 4.7dB, respectively. The compensation circuit consumes 1.1mW.