Study and design on automatic gain control circuit for WCDMA repeater uplink system

In order to communicate successfully for mobile stations in signal dead zone, this paper presents an inverse-gain- feedback dual-loop automatic gain control (AGC) circuit used in WCDMA repeater uplink system. The repeater employs two stages radio frequency AGC circuits, which are gain control of input part and output part respectively, so that the system can work normally and automatically control the output power. Agilent advanced design system (ADS) is used as a simulation tool to analyze the performance. The results show that it is performed well, which has the characteristic of good frequency selectivity and channel selectivity, steady controllable output, large range of AGC gain and wide range of output power. Therefore, the proposed system is suitable to solve the problem of the dead zone in WCDMA communication.