Dual mixer downconversion architecture using complex mixing signals: enabling solutions for software defined radios

Abstract

A dual mixer architecture using complex mixing functions to perform RF downconversion is described. This architecture eliminates the need for the image-reject and IF filters present in the heterodyne architecture, while achieving better LO leakage, 1/f noise. and second-order intercept performance than the direct conversion architecture. This architecture, implemented in a 1.8 V, 0.18 /spl mu/m CMOS process, achieves a maximum IIP2 of 85 dBm, a baseband 1/f noise corner frequency of less than 100 kHz, a LO-RF leakage equaling -138 dBm, and an operating frequency ranging from 400 MHz to 2.5 GHz.