AUTOMATIC GAIN CONTROL SYSTEM

摘要

PURPOSE: To provide an automatic gain control system improved in the delay of a response to excessive input signals. CONSTITUTION: This automatic gain control system is provided with an integration circuit 26 for integrating a difference between the value of the output signals of a variable gain amplifier 1 for amplifying reception signals and a target reference value in which the output signals of the integration circuit 26 are supplied to the same amplifier as gain control signals. To the system, a means for detecting saturation caused by the excessive reception signals in a circuit for constituting a receiver and the means for forcedly replacing the value of the integration circuit 26 with the value for turning the amplifier to prescribed low gain when the saturation is detected are added. It is desirable that the gain control signals of the output of the integration circuit 26 are supplied to the gain control terminal of the variable gain amplifier 1 for amplifying transmission signals. Also, it is desirable that transmission power control correction signals are generated and correction signals are added to AGC signals supplied to the amplifier for transmission when control bits for indicating the increase/decrease of transmission power are transmitted from a base station.