An improved 3 V 2 GHz BiCMOS image reject mixer IC

A 2 GHz BiCMOS image reject mixer is described in this paper. A novel combination of 90/spl deg/ phase shifter networks and a gain control system are used to obtain high image rejection despite local oscillator frequency variation due to channel selection, intermediate frequency (IF) adjustment and process fluctuations. A 35 dB min. image rejection is obtained in a 200 MHz RF bandwidth centered at 2 GHz and a 200 MHz IF. Furthermore, the gain control system allows a 25 dB min. image rejection for IF adjustment from 100 MHz to 300 MHz. The conversion gain of the mixer is 10 dB and the IP3 is -4,5 dBm referenced to the input. The overall current consumption is 15 mA from a +3 V supply. The mixer has been integrated in a front end IC including an antenna preamplifier in a silicon BiCMOS process.