A DESIGN AND SIMULATION STUDY OF ZERO-IF GILBERT-CELL MIXER FOR WIMAX RECEIVERS

Abstract

Differential approach is becoming highly preferred in RFIC (radio frequency integrated circuit) design due to its advantages, particularly its high immunity to common-mode noises, satisfactory rejection of parasitic coupling, and increased dynamic range. One particular RF front-end building block that is often designed as differential circuit is the mixer. This paper presents a study and design of a differential mixer, particularly the Gilbert-cell or double-balanced mixer implemented on a zero-IF (zero-intermediate frequency) or direct-conversion architecture in a standard 90nm CMOS (complementary metal-oxide semiconductor) process operating at frequency of 5GHz, which is a typical frequency for WiMAX (worldwide interoperability for microwave access) receiver. Impedance matching was necessary to fully optimize the mixer design. The zero-IF Gilbert-cell mixer design achieved conversion gain of 11.46dB and noise figure of 16.53dB, comparable to other mixer designs.