Design_and_Operation_of_AGC_LoopsTUTORIAL DESIGN AND OPERATION OF AUTOMATIC GAIN CONTROL LOOPS FOR RECEIVERS IN MODERN COMMUNICATIONS SYSTEMS his article is intended to provide insight into the effective operation of variable gain amplifiers (VGA) in automatic gain control (AGC) applications. Figure 1 is a general block diagram for an AGC loop. The input signal passes through the VGA to produce the output level to be stabilized. The detector’s output is compared against a setpoint voltage to produce an error signal, which is then integrated to produce a gain control voltage. This is applied to the control input of the Fig. 1 VGA-based AGC VGA. The attenuator shown beloop block diagram. ……