A 1.5 V CMOS VGA based on pseudo-differential structures

Abstract

A CMOS variable-gain amplifier that works down to V/sub DD/=1.5 V is described. The gain characteristic is arranged to be a nearly exponential function of control voltage by a novel circuit topology that utilizes triode-biased transistors in pseudo-differential configurations. This circuit is designed using a 0.35 /spl mu/m CMOS process and operates at a 3-dB frequency of 21 MHz with a maximum power consumption of 24.8 mW.