逆F类功放数字预失真改进算法

针对逆F类射频功率放大器高效率实现带来的严重的非线性失真,提出基于幅度索引的查找表(LUT)模型数字预失真改进算法,以获得具有高线性和高效率的逆F类射频放大系统。由于逆F类功放复杂的特性曲线,传统LUT数字预失真算法已经不能很好地拟合功放模型,为此采用非均匀取点拟合,并且结合多项式、EWMA和平滑等曲线拟合方法。实验结果表明:运用该方法,使3载波WCDMA信号施加到中心频率为930 MHz的逆F类功率放大器后的非线性失真现象明显改善。

Improved Algorithm of Inverse Class-F Power Amplifier Digital Pre-distortion

Considering the inverse class-F amplifier linearity sacrifice to achieve high efficiency,the paper proposes a digital pre-distorter algorithm of lookup table （LUT） model based on amplitude index to realize a high-linearity and high-efficiency inverse class-FRF amplifier system. Because of the complicated nonlinear characteristics of inverse class-F power amplifier,the traditional LUT digitalpre-distorter algorithm can not fit PA model very well. So non-uniform point taking is adopted, combining with curve fitting methodssuch as polynomial,EWMA and smoothing. The experiment results show that through this method,the nonlinear distortion for applying a3-carrier WCDMA signal to the inverse class-F power amplifier with a center frequency of 930 MHz is significantly improved.