Low voltage low power CMOS AGC circuit for wireless communication

This paper describes a new technique for realizing CMOS digitally controlled, dB-linear variable gain amplifier (VGA) circuit. The circuit is developed taking into account system level issues for a direct conversion receiver. Besides being effective and simple to use from a system point of view, the developed VGA offers precise gain control, high linearity and low power consumption. The circuit can operate in a current domain or a voltage domain mode with single ended or fully differential signal handling capability. The proposed VGA circuit is implemented using a novel class AB operational transconductance amplifier and current division networks. Simulation results are included.