Research Of Predistortion Of High Power Amplifier

With reference to the international DTTB standards and learning from the domestic HDTV researches, Tsinghua University proposed the transmission protocol of Terrestrial Digital Multimedia-Television Broadcasting--DMB-T. It is based on the OFDM technology. There is a main disadvantage about OFDM technology: high PAPR(peak to average power ratio).This causes much distortion when the signals pass a HPA(high power amplifier).In this paper, we overview the research on HPA linearization techniques. The advantages and disadvantages of some typical linearization techniques are analyzed with detailed analysis on the effect of HPA non-linear on OFDM signals. Some crucial problems that should be paid more attention concerning HPA are presented systematically.Also, we make analysis on the effects of HPA nonlinear distortions on the OFDM transmitted signals. Based on our deep and detailed research, we completed a hand-controlled predistorter and also a semi-auto predistorter. They all worked well in our lab. We built a platform for the research of adaptive predistorter.