Automatic Gain Control for High Dynamic Signals Using Feedforward Technique

Abstract

This paper proposes Automatic Gain Control (AGC) implementation using feedforward technique to ensure the input signal dynamic range is not in saturation level or below noise tolerance level for the succeeding analog to digital converter (ADC) block. Using this technique, AGC implementation and Received Signal Strength Indicator (RSSI) measurement can be done simultaneously. AGC is a closed loop feedback control system which adjusts the arbitrary received signal strength to a predetermined level. It is employed to delimit the dynamic range of the signal and hence reducing the power consumption of ADC. RSSI is used to determine the signal strength at the input of the receiver. It is estimated by measuring the voltage at the detector whose output voltage is proportional to the input signal level. In the proposed design, AGC maintains the constant output signal level of −20 ± 2 dBm for the input signal varying from −58 to −1 dB with a dynamic range of 57 dB.