New AGC circuitry for digital receiver

A new Automatic Gain Control (AGC) circuitry is proposed in this paper. The feedback control scheme of subsequent AGC closed-loop in conventional AGC frame is converted to forward control scheme in new circuitry. The power detector and the loop filter are shared by two cascaded AGC loops in new AGC circuitry, so the gain errors in foregoing AGC closed-loop can be corrected by subsequent AGC closed-loop, and total gain errors of new AGC circuitry is determined only by the gain errors in subsequent AGC closed-loop. Simulation and measurement results verify that the new AGC circuitry not only improved the gain control precision, but also decreased the response time, compared with conventional AGC circuitry.