Research On High Efficiency And Linearization Techniques Of Amplifiers Based On Peak-power Conctrolled

The linearization of power amplifier is a very important and key technology in modern wireless communication system. It can reduce distortions within the signal bandwidth, weaken adjacent channel interference, and meanwhile enhance the efficiency of power amplifier. Digital Predistortion is a research hotspot of the most popular ways among all linearization techniques, due to its numerous advantages. In this dissertation, we start with the expansion of digital Predistortion and aim at improving the linearity, increasing the efficiency and minimizing the risk of power amplifier. Following aspects have been lucubrated on.Firstly, we introduce the inherent nonlinearity and memory effect of power amplifier(PA). The reason why the memory effect produces and the methods to recede it have been presented. Then the basal principle of digital predistortion has been explained, including some baseband power amplifier models and their merit and demerit. Furthermore, some learning sructures, gain estimation and time delay estimation have been introduced.Then, based on the analysis of high peak to average ratio signal influencing on the efficiency of the amplifier, we study how to effectively reduce the signal peak in order to improve the power amplifier efficiency. Limiting amendment method and the corresponding concrete implementation process is proposed. At last, its feasibility is verified in the MATLAB software. In addition, the relationship between the expansion of digital predistortion and the predistortion result and the PA is what we focus on, namely deteriorating linearity improvement, reducing the power amplifier efficiency and increasing the chance of damage power amplifier. We find that the predistortion effect can be best when the predistortion input signal average power, predistortion output signal average power and the training signal average power meet a certain relationship. Secondary clipping method is proposed in order to weaken predistortion extensibility, and the quadratic clipping method is simulated in software simulation. Moreover, the detail discussion is presented.Finally, the evaluation board based on peak processing digital predistortion is presented, including power amplifier module, FPGA development board, and frequency conversion module. Doherty amplifier and power amplifier protection circuit design are analyzed. And the overall digital predistortion testing procedures and the measured results are also given. Measurement results show that the ACPR is improved by 17 dB when digital predistortion is added; The peak to average ratio of the output signal of digital predistortion is decreased by 1.4dB when the quadratic clipping is used, which makes the average power increasing from 39.5dBm to 40.5dBm and the average efficiency of power amplifier growing from 32.8% to 35.7%.