LOW-VOLTAGE PERFORMANCE OF A MICROWAVE CMOS GILBERT CELL MIXER

This paper demonstrates the low voltage operation of a doubly balanced Gilbert mixer fabricated in a 0.8-mu m CMOS process and operating as both a down-converter and an upconverter. As a down-converter with an RF input of 1.9 GHz, the mixer has a single sideband noise figure as l ow as 7.8 dB and achieved down-conversion gain for supply voltages as low as 1.8 V. As an up-converter, the mixer demonstrates 10 dB of conv ersion gain at an RF frequency of 2.4 GHz with an applied local oscill ator (LO) power of -7 dBm and LO-RF/LO-IF isolation of at least 30 db. Up-conversion gain was achieved over a 5-GHz bandwidth and at supply voltages as low as 1.5 V. The mixer presented demonstrates the lowest single side band noise figure for a CMOS doubly balanced down-converti ng mixer and the highest frequency of operation for a mixer fabricated in CMOS technology to date.