Abstract: A down-converting mixer fabricated with 0.18μm RF CMOS technology is designed for OFDM-UWB applications.Differing from conventional Gilbert cell topology,a differential topology is proposed and applied in order to reduce the noise contribution and disturbance from the large signal of the local oscillation,as well as to lower the DC consumption of the mixer.The test result demonstrates that over the intermediate frequency band of 4～252MHz,the mixer achieves conversion gain of above 2.5～7.8dB,NF of 22.5～26dB,isolation among the ports of about -50dB,and consumes about 8mA under a 1.8V supply.

Key words: CMOS, OFDM, UWB, Mixer