Distortion-characteristic estimation predistorter for high efficiency power amplifiers

Abstract

Power amplifier (PA) is one of important components in wireless communication system. However, its non-linear and memory characteristic cause harmful distortion, which significantly decreases the power efficiency and wastes electronic energy since the power of PA needs back off. To overcome the non-linear and memory problems, a novel method based on distortion-characteristic estimation algorithm is developed in this study. The main innovation of this study is manifested in two aspects: first, the authors use well designed training signals to estimate the distortion characteristic of the PA; second, a novel PA characteristic estimation algorithm is developed in order to calculate the optimal state of the ideal predistorter that behaves like the inverse characteristic of PA theoretically. Since this novel method does not require the error between original signals and feedback signals, it can avoid the significant errors caused by the time mismatch between source signals and feedback signals, and can increase the power efficiency of the PA. The simulation results validate the performance increase and the synchronisation-error immunity over the existing simplified filter look up table method.