Adaptive control method for a feedforward amplifier

A feedforward amplifier, which is composed of several components, is an open loop system. Therefore, feedforward amplifiers are apt to deteriorate in their performance according to environmental changes, even though the cancellation performance and the linearization bandwidth of feedforward systems are superior to other linearization methods. A control method is needed to maintain the original performance of feedforward amplifiers or to keep the desired performance within small error bounds. In this paper, an adaptive control method, using the steepest descent algorithm, which has a good convergence characteristic and is easy to implement, is suggested. The characteristics of the suggested control method are compared with the characteristics of other control methods and the simulation results are presented.