Wide Baseband Analog AGC System with Large Dynamic Range Based on Peak Power Detection

A 500MHz to 1.9GHz analog automatic gain control (AGC) system with large dynamic range in a satellite-borne communication receiver is reported in this paper. The system consists of a variable gain unit which is realized by voltage-variable attenuators (VVA), a power detector and a feedback loop. In order to investigate the influence of input noise power in wide baseband on the dynamic range of the AGC system, a comparative experimental study has been carried out to figure out the difference of dynamic range deterioration between peak power detection mode and that of root mean square (RMS) detection. Experimental results demonstrate that the dynamic range of the AGC loop based on peak detection is wider than that of the loop based on root mean square (RMS) detection for the baseband as wide as from 500MHz to 1.9GHz. The measured dynamic range of the AGC system in this work is -70dBm to -8dBm based on peak detection, while it is -65dBm to -8dBm based on RMS detection for the same AGC loop.