【作者】 丘春辉；

【导师】 陈向东；

【作者基本信息】 西南交通大学 ， 通信与信息系统， 2008， 硕士

【摘要】 为节约频谱资源,新兴的数字通信技术常具有多载波或者高峰/均功率比等共同特点,对系统的线性化指标提出了更为苛刻的要求。因此,射频功率放大器的线性化技术成为无线通信领域的一个重要课题,也是近年来国内外的一个研究热点。而前馈技术是线性化效果最好,也是目前最热门的线性化技术。前三章回顾总结了非线性失真的特性以及常用线性化技术的基本原理及其相互之间的异同。第四章首先提出主放大器的反射信号是造成前馈环路中幅值失配和相位失配的重要原因之一,并分析该反射信号对前馈两个环路中误差信号的幅值和相位的影响及对策,然后推导出误差信号中幅值、相位的变化量与反射信号所引起的幅值、相位失配之间的计算公式。最后针对该反射信号,设计了一个前馈放大电路。结果显示,改进的前馈电路有效减小了前馈环路的幅值失配和相位失配,并且有效降低了输出信号的非线性失真。第五章先采用相关法和最小功率检测法仿真了一个自适应前馈电路。然后针对其输出功率的不足,并结合第四章关于幅值失配和相位失配的原因分析,通过引入一个反馈电路和一个前馈电路,对该自适应前馈电路进行改进。测试证明,这种改进的自适应前馈电路其三阶交调失真降低了10dB,输出功率增加了约2dB。更多还原

【Abstract】 For the sake of saving the frequency source, the fashion digital communication technologies always have the common characteristic of multi-carrier and high ratio of apex to average, which bring forward much more strict linearization target to the RF system. So the linearization technology for RF power amplifiers becomes one of the important items in the wireless communication theory. The feedforward technology has the best effect for linearization and becomes the most popular linearization technology.The characteristics of the nonlinear distortion and the principium of usual linearization technologies have been proposed during the chapter one to chapter three, and so the commons and differences between them.The chapter 4 first indicates that one of the important causes of amplitude-mismatch and phase-mismatch based on the traditional feedforward circuit is the main PA’s echo. The effect on the amplitude and phase of bi-loops’ feedforward circuit’s error signal brought by the echo and some measures have been analyzed, thus the expressions of variations in amplitude and phase of the error signal against amplitude-mismatch and phase-mismatch have been proposed later. At last, a feedforward circuit against the echo has been designed to decrease the nonlinearization distortion effectively.At the chapter 5, the merits and disadvantages of the usual bi-loops adaptive feedforward circuit by decreasing the nonlinearity distortion and exporting enough power are discussed first. We introduce another feedforward circuit by coupling some signal from the input of the main power amplifier to the input and output of the auxiliary power amplifier to reduce more IM3 and increase the output power. The results show that the IM3 reaches below -75dBc, which is much more acceptable than before by 10dB, and the output power has increased by 2dB.更多还原