An Adaptive Predistortion Method based on Orthogonal Polynomial Expansion for Nonlinear Distortion Compensation.

Adaptive predistorter is an effective technique to compensate nonlinear distortion in a power amplifier. As a method to improve the parameter convergence speed in the predistorter, a series expansion technique with an orthogonal polynomials has been proposed. In this paper, we propose an adaptive predistorter based on orthogonal polynomial for the power amplifier with memory effect, where the parameters of predistorter are determined so as to minimize out-of-band radiation components detected by high pass filter (HPF). With computer simulation using the Advanced Design System (ADS) software, we show that the adaptive predisterter using orthogonal polynomials achieves faster convergence time than that with that of non-orthogonal one, while nonlinear distortion is compensated by memory predistorter using orthogonal polynomials.