A Piecewise RLS-Based Digital Predistortion Scheme for Power Amplifier

The recursive least square(RLS) algorithm is a popular candidate for extracting parameters in digital pre-distortion because of its fast convergence and high accuracy. However, it suffers from instable convergence which leads to undesirable peak values on the error curve. In this paper, a piecewise RLS-based scheme for RF power amplifier digital pre-distortion is proposed. The proposed scheme divides the input signal into two categories, peak and non-peak, then by using RLS algorithm, it generates two sets of pre-distortion parameter, which are subsequently applied to peak signals and non-peak signals respectively. Simulation results show that the piecewise RLS is superior to the traditional method in terms of the stability and the adjacent channel power ratio (ACPR) improvement.