A digitally controlled dB-linear CMOS AGC for low voltage mixed signal applications

A new digitally controlled current mode automatic gain control (AGC) circuit is presented. The proposed circuit uses a novel digital control technique to provide a dB-linear gain control. The circuit is based on binary weighted current mirrors leading to a simple structure that is suitable for low voltage low power applications. When used in wireless communication applications, the AGC can effectively combine with the down-conversion mixer. The control range of a single stage AGC is -25 dB. Simulation results are included.