采用射频预失真的新型大功率Doherty功放设计与实现

Design and implementation of a new high-power Doherty power amplifier using RF predistortion

针对大功率射频功率放大器在设计研制上都存在较大困难,特别是大功率难匹配,实现大功率后线性度差、效率低等问题,设计一种适用于无线通信基站系统的二路大功率Doherty功率放大器。采用新型射频预失真芯片构建高集成度的线性化电路,改善该功率放大器的线性。仿真结果表明,在饱和功率回退6 dB时,该功率放大器平均输出功率可达到100 W,效率可达到44.158%,从而实现高效率和大功率的输出;加入预失真电路后,功放线性改善了20 dB。实测结果验证了仿真的一致性。

Good high-power RF power amplifiers are difficult to design because of issues like power matching, nonlinearity and low efficiency. In this paper, we propose a new way of designing two-way high-power Doherty amplifiers which are commonly used in cellular base stations. Based on the latest RF predistortion chip, we design a highly integrated lineariza- tion circuit to improve the linearity of the Doherty amplifier. Simulation results have shown that at 6dB back-off from the saturated output power, the proposed amplifier achieves an average output power of 100 W with an efficiency of 44.2%. In other words, the predistortion circuit improves the linearity of the Doherty power amplifier by an extra 20 dB. The simula- tion results are further verified by the experimental results.