无线通信射频功率放大器非线性失真优化设计

摘要

针对无线通信系统中射频功率放大器的非线性失真问题进行研究,设计数字预失真结构补偿功放的非线性特性.然而,OFDM信号的高峰均比使功放工作在饱和区,产生严重的非线性饱和失真,并且产生这种饱和失真的非线性很难通过数字预失真得到补偿,因此提出了联合峰均比抑制的数字预失真新结构.峰均比抑制采用选择映射法和压扩变换相结合的融合算法,最大限度降低功放输入信号的峰均比,避免功放工作在饱和区,提高功放效率.为了优化联合结构的收敛速度提出自适应LS-LMS算法,并应用到基于记忆多项式模型的数字预失真间接学习结构中.仿真结果表明,联合峰均比抑制的自适应数字预失真性能优于单独的自适应数字预失真,能够有效地消除高峰均比信号通过功放饱和区产生的非线性失真.%A new structure of the combined PAPR reduction and digital predistortion is proposed.Joint mapping method and pressure expansion transform are used as the PAPR reduction algorithm,which can lower power amplifier input signal PAPR,avoid power amplifier working in the saturated zone,and improve the efficiency of power amplitier.In order to improve the convergence rate of the joint structure,the adaptive LS-LMS algorithm is put forward,and the memory polynomial model is applied to the predistortion indirect learning structure.Simulation results show that the joint PAPR reduction of adaptive digital predistortion is superior to the single adaptive digital predistortion,it can effectively eliminate the nonlinear distortion caused by high PAPR signal through amplifier saturation zone.