针对射频功率放大器的非线性问题, 提出一种基于两个复量多项式的模拟预失真电路, 并根据射频功率放大器的响应用LMS(最小均方)算法自适应优化多项式的系数, 从而使功率放大器的线性性能达到最佳。该预失真器的优点是电路简单, 运算量少, 适用于宽带通信。基于双频信号和WCDMA(宽带码分多址)信号对该预失真器进行了仿真测试。实验结果表明, 该预失真线性化方法对交调失真分量抑制效果明显, ACPR(邻信道功率比)可改善至56.1 dB, 对功率放大器的非线性具有良好的补偿效果。

In view of the nonlinearity problems of RF power amplifiers, a two complex polynomials-based analog pre-distortion circuit is proposed in this paper, and the coefficients of these polynomials are adaptively optimized according to the response of the power amplifier using the LMS algorithms, resulting in the optimum linearity of the power amplifier. This pre-distorter is characterized in simple circuit, little computation and suitability for broadband communications. Furthermore, it is experimentally simulated and tested on the basis of dual-band and WCDMA signals. The results indicate that the pre-distortion linearization method is obviously effective to inhibiting Intermodulation (IM) distortion components and improves the Adjacent Channel Power Ratio (ACPR) to 56.1 dB, well compensating the nonlinearity of the RF power amplifiers.