On the design of constant settling time AGC circuits

The generalized design of Automatic Gain Control (AGC) circuits that have constant settling time is described. Each of the major components of the AGC circuit is modeled and the criteria to obtain a gain settling time independent of the absolute gain are determined. The method developed works with arbitrary monotonic nonlinear functions in the gain control characteristic of the variable gain amplifier. Several AGC circuits are simulated at the behavioral level to show the benefits of the technique developed.