高线性大功率前馈功率放大器的设计

发布时间：2019-06-17 12:49

【摘要】：随着无线通信技术的发展,频谱利用率越来越高,对器件的线性度要求也越来越高。功率放大器作为无线通信发射机中非线性最严重的器件,如何优化其线性度一直是人们关注的焦点。本课题利用前馈技术对已有的259.9MHz~270MHz频段、输出功率为200W的功率放大器进行了线性度优化。本文首先简要介绍了功率放大器线性化技术研究的背景与意义以及功率放大器常用的指标;分析了功率放大器的非线性特性;比较了几种常见的线性化技术的优缺点。基于优化程度高、带宽较宽等优点,本文决定采用前馈技术对已有放大器进行线性度优化。本文着重介绍了前馈功率放大器的结构以及组成系统的关键器件:矢量调制器、误差放大器、耦合器、延时器等。给出了各个器件的实现方案以及测试结果。最后对整个前馈功率放大器进行了调试,得到了较为理想的结果。在双音间隔9.5MHz,输出200W时,能将主放大器的三阶互调(IMD3)优化21dB以上,所得到的前馈放大器在输出功率为49.8dBm的同时,IMD3约为-62dBc。本文的最后对上述搭建的系统进行了优化,给出了优化方案并得到了最终的测试结果。优化之后的前馈功率放大器主通路插损降低了0.48dB,使得最终的输出功率达到50.3dBm,满足设计要求。
[Abstract]:With the development of wireless communication technology, the spectrum efficiency is getting higher and higher, and the linearity of devices is required to be higher and higher. As the most nonlinear device in wireless communication transmitter, how to optimize its linearity has always been the focus of attention. In this paper, the feedforward technology is used to optimize the linearity of the existing 259.9MHz~270MHz power amplifier with output power of 200W. In this paper, the background and significance of power amplifier linearization technology and the common indexes of power amplifier are briefly introduced, the nonlinear characteristics of power amplifier are analyzed, and the advantages and disadvantages of several common linearization techniques are compared. Based on the advantages of high optimization degree and wide bandwidth, this paper decides to use feedforward technology to optimize the linearity of existing amplifiers. In this paper, the structure of feedforward power amplifier and the key components of the system are introduced, such as vector modulator, error amplifier, coupler, delay timer and so on. The implementation scheme and test results of each device are given. Finally, the whole feedforward power amplifier is debugged, and the ideal results are obtained. When the two-tone interval is 9.5 MHz and the output is 200W, the third-order Intermodulation (IMD3) of the main amplifier can be optimized above 21dB. While the output power of the feedforward amplifier is 49.8dBm, the IMD3 is about-62dBc. At the end of this paper, the above system is optimized, the optimization scheme is given and the final test results are obtained. After optimization, the insertion loss of the main path of the feedforward power amplifier is reduced by 0.48dB, so that the final output power reaches 50.3dBm, which meets the design requirements.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN722.75

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