Performance comparison of adaptive digital predistortion algorithms using adaptation time for mobile WiMAX power amplifier applications

Abstract

In this paper, we propose that adaptation time be considered a parameter for evaluating the performance of digital filter algorithms in adaptive digital predistorted high-power amplifiers. An adaptive predistorted high-power amplifier with an average power of 37.5 dBm was designed and fabricated for mobile worldwide interoperability for microwave access (WiMAX) test signals. For performance comparisons using adaptation time, several effective algorithms (such as the least-mean-squares (LMS), recursive-least-squares (RLS), and affine projection (AP) algorithms) were implemented. According to the experimental results, the RLS and AP algorithms achieved a similar linearity improvement of 11 dBr. However, the AP algorithm had the advantage of a faster adaptation time than the other algorithms.