A nonlinearity predistortion technique for HPA with memory effects in OFDM systems

Memory effects of high power amplifiers (HPAs) can no longer be ignored when input signals have relatively broad bandwidth. In this paper, a new adaptive method called two-dimensional look up table (2D LUT) is presented to linearize HPAs with memory effects. Different predistortion factors are distributed to the same current inputs with different historical states, in order to eliminate the memoryless characteristic of 1D LUT. Simulation and experimental results show that 2D LUT suppresses the signal distortion more effectively with a linearity improvement of 20 dB.