Analysis and design of an integrated quadrature mixer with improved noise, gain and image rejection

The analysis of a quadrature mixer based on the CMOS double-balanced mixer is presented. The noise, image rejection, conversion gain, and linearity of the quadrature mixer are compared to that of a Gilbert mixer under square wave and sinusoidal LO drive. It is shown that the quadrature mixer exhibits a 3 dB improvement in noise and conversion gain, and improved image rejection, compared to a pair of Gilbert mixers when the LO signal is a large amplitude sine wave.