基于新型二维核函数动态X参数的功放建模

Modeling of power amplifier based on dynamic X-parameter of new two-dimensional kernel function

为了更准确地描述带有记忆效应的射频(RF)功放特性,基于传统的动态X参数模型,结合功放长期记忆效应以及短期记忆效应机理,提出一种新型动态X参数功放建模方法。新模型保留X参数模型的静态核函数,利用双记忆路径模型提取出表征记忆效应的非线性函数,替换动态核函数。采用输出信号为幅度与频率双变量的新型反馈(FB)结构,引入时变频率变量而简化动态核函数为二维核函数。使用MW6S010N设计功放并建模,由仿真可知,新模型在单音大信号及码分多址(CDMA)信号激励下,均能正确表征功放特性,归一化均方误差(NMSE)较静态X参数模型、传统动态X参数模型以及前馈(FF)结构X参数模型分别减少8.0 d B、6.3 d B、2.5 d B。结果表明该模型能够更加准确拟合带有非线性记忆效应功率放大器的特性。

In order to accurately describe the characteristics of Radio Frequency（ RF） power amplifier with memory effect, a new dynamic X-parameter amplifier modeling method based on traditional dynamic X-parameter model was proposed by combining with long-term memory effect and short-term memory effect. The new model preserves static kernel function of Xparameter model. A nonlinear function of memory was extracted by using the two-memory path model to replace dynamic kernel function. A novel Feed Back（ FB） structure was proposed in which the output signal is a bivariate of amplitude and frequency, and the time-varying frequency variable was introduced to simplify the dynamic kernel function as a twodimensional kernel function. The power amplifier was designed and modeled by the MW6S010 N transistors. Simulation results indicate that the new model can correctly represent the characteristics of power amplifier with the excitation of single-tone large signal and Code Division Multiple Access（ CDMA） signal. The Normalized Mean Square Error（ NMSE） of the proposed method was decreased by 8. 0 d B, 6. 3 d B and 2. 5 d B, respectively, in comparison with static X-parameter model, traditional dynamic X-parameter model and Feed Forward（ FF） structure X-parameter model. It is proved that the proposed model can more accurately fit the characteristics of power amplifier with nonlinear memory effect.