【作者】 梁雅琴；

【导师】 贾建华；

【作者基本信息】 同济大学 ， 通信与信息系统， 2007， 硕士

【摘要】 射频功率放大器是现代无线通信系统发射机中的关键模块，其性能的优劣直接影响着通信的质量和效率，目前大多数的功放模型和线性化方法都局限于窄带应用，当信号带宽增大导致放大器记忆效应明显时，传统的线性化方法对功放非线性的补偿效果就会变得很差，为了改善宽带放大器的线性度，近年来考虑记忆效应的功放建模和线性化方法成为新的研究趋势。深入研究宽带通信系统中功率放大器的非线性机制及记忆效应，分析了记忆效应的现象及产生原因，论述了三类非线性放大器模型：无记忆模型，准无记忆模型和考虑记忆效应的模型。分别用极坐标，正交拓扑以及多项式函数的形式推导了准无记忆模型的输入输出关系，归纳出利用双音测量数据提取多项式系数的步骤。重点论述了记忆多项式模型的构造原理，包括一致时延项模型和非一致时延项模型，比较了它们的建模策略和复杂度，并以Motorola公司的MRF9742功放管为例，提出了一种新的更易于实现的非一致时延分支项算法：类正弦函数确定法。利用记忆多项式建模法对传统预失真技术进行改进，提出非一致时延记忆多项式预失真技术，并着重分析了记忆预失真发生器的构造原理。设计了一个非一致时延记忆预失真线性化功放系统，利用ADS仿真分析MRF9742模型的非线性特性和记忆效应，比较了传统预失真和非一致时延预失真的线性化效果，仿真结果证明在宽带应用中，用类正弦函数算法构造的非一致时延预失真能迅速有效地抑制输出频谱中的互调失真产物，大幅提高功率放大器的线性度。更多还原

【Abstract】 Radio frequency power amplifier is the key component of the transmitter inmodem wireless communication system, and its performance highly affects thecommunication quality and efficiency. At present, most power amplifier models andlinearization methods are limited to narrowband application. When memory effects ofthe amplifier become obvious due to widen of signal bandwidth, compensation effectsof the traditional linearization technique can not be satisfying. In order to improve thelinearity of wideband amplifiers, research on modeling and linearization of poweramplifiers considering memory effects has become a new trend in recent years.Nonlinearity and memory effects of power amplifiers in widebandcommunication system are deeply analyzed including the phenomenon and sources ofmemory effects. There types of nonlinear amplifier models: memoryless model,quasi-memoryless model and memory model are presented. First, input-outputrelations of the quasi-memoryless model are developed respectively in polar,quadrature and polynomial function versions. Then the emphasis is laid on theconstruction principle of the memory polynomial model including memorypolynomial with unity time delay taps and memory polynomial with non-uniformtime delay taps. Modeling strategy and complexity of these two memory models arecompared and a new algorithm of realizing non-uniform time delay taps:sinusoidal-like function computation is put forward bases on MRF9742 powertransistor.Traditional predistortion technique is improved using memory polynomialmodeling method. Non-uniform time delay memory polynomial predistortiontechnique and the realization of memory predistorter are represented in details. On thebasis of above analyses, a practical MRF9742 linearization power amplifier system isdesigned. First, nonlinear characteristics and memory effects of MRF9742 model aresimulated and analyzed using ADS software. Then linearization effects of traditionalpredistortion and non-uniform time delay predistortion are compared and the simulation results prove that non-uniform time delay predistortion techniquedepending on sinusoidal-like function computation can suppress the intermodulationdistortion products of the power amplifier system and improve its linearity greatly.更多还原