高效率E类射频功率放大器的设计(1)

宁夏理工学院毕业设计

摘要

随着信息产业的迅速发展，人们对无线通信系统提出了越来越高的要求。射频功率放大器在无线通信系统中占有重要作用，将直流电源的直流功率转换为输出信号。如何设计出性能良好的功率放大器已经成为人们广泛关注的课题。

本文首先介绍了射频功率放大器研究的背景，分析了国内研究成果与国外研究成果的差距，并介绍了射频功率放大器的研究意义。其次分别从射频功率放大器的工作的频带、匹配网络、电流导通角、工作状态等角度介绍了其分类。然后分析了A类功率放大器、B类功率放大器、AB类功率放大器、C类功率放大器的功率与导通角存在的关系，导通角减小，效率会增大，但基波振幅会减小，当导通角减小到零时，效率理论上达到了100%，但电路中已经没有了信号。通过减小导通角提高效率已经行不通，此时引入开关类型D类功率放大器。D类功率放大器的设计主要是要求功率管在导通时，即功率管有电流流过，饱和管压降为零，截止时，流过功率管的电流为零，饱和管压降不为零。由于功率管极间电容和电路中的分布电容，将使功率管在导通至截止和截止至导通的开关转换瞬间集电极上的电压和电流均不为零，即集电极上有功率损耗，也就限制了D类功率放大器不能应用于高频的特性。如果在电路上加以改进，使电子器件在通断转换瞬间的功耗尽可能地减少，使通断的转换时间尽可能地缩短，从而提高效率，即构成E类功率放大器。

E类功率放大器主要是利用功率管截止时，使集电极电压uce在集电极电流ic=0以后才开始上升；功率管导通时，使集电极电流ic在以后才开始出现，保证使功率管从导通至截止或从截止至导通的开关期间，集电极电流ic和集电极电压uce不会同时出现，只有这样，消耗在集电极上的功率才能为零，功率管的功耗最小，效率最高。

随着信号处理技术的发展和功率器件性能的提高，以E类功率放大器为代表的开关类功率放大器，正在以其高效率的优势日益受到人们的重视。总之，射频功率放大器的发展还有很大空间和工作要求，致力于更高效率和更好性能的研究，将会更好的满足飞速发展的信息技术的要求。

关键词：射频功率放大器；E类射频功率放大器；高效率；阻抗匹配

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宁夏理工学院毕业设计

Abstract

As the development of information industry，the wireless communication systems are required to be more and more efficient.For the importat role of RF power amplifiers in wireless communication system，it has become aroused general interest that how to design a well performance RF power amplifiers.

This paper introduces the research background of RF power amplifier, analyzes the domestic and foreign research results of research gaps, and introduces the research significance of RF power amplifier firstly. Secondly, from the RF power amplifier, matching network, the working frequency current conduction angle, working state angle introduced its classification. Followed by an analysis of class a power amplifier, class B power amplifier, class AB power amplifier, class C power amplifier power and conduction angle relationship exists, the conduction angle decreases, efficiency will be increased, but the fundamental wave amplitude decreases, when the conduction angle decreases to zero, efficiency theory reached 100%, but the circuit have no a signal. By reducing the conduction angle to improve efficiency has failed, then introducing the switch types of class D power amplifier. Class D power amplifier is designed to require power tube conduction time in, namely the power tube current flows, saturation voltage drop to zero, at the end, through the power tube current is zero, the saturation voltage drop is not zero. As a result of power transistor interelectrode capacitance and circuits in the distributed capacitance, will make the power tube in conduction to the cutoff and end to the turn-on switching instant collector on the voltage and current are not zero, the collector has the power loss, will also limit the class D power amplifier can be applied to high frequency characteristics.If the circuit is improved, so that the electronic device in the on-off conversion instantaneous power consumption reducing as far as possible, so that the on-off switching time shortened as much as possible, thereby improving the efficiency, which constitute the class E power amplifier.

Class E power amplifier is the main power tube is closed, so that the collector voltage uce current collector in ic = 0 then began to rise; power tube is conducted, the collector current of ic in later began to appear, to ensure that the power tube from conducting to the cutoff or from the

II

宁夏理工学院毕业设计

end to the conduction of the switch during the period, the collector current ic and the collector voltage uce would not appear at the same time, only in this way, the power consumption in the collector to zero, the power tube minimum power consumption, highest efficiency.

With class E power amplifier as the representative of the switching power amplifier, is its high efficiency advantage is increasingly valued by people.Overall，it is a broad space for development of RF power amplifier，only by designing RF power amplifiers which have higher efficient and better performance; it will be meeting in the rapid development of information technology in our society.

Keywords:

RF Power Amplifier;Class E Power Amplifier;High efficiency;Impedance

matching

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宁夏理工学院毕业设计

目录

摘要 .................................................................... I Abstract ................................................................ II 1绪论 .................................................................. 1 2 射频功率放大器 ........................................................ 2 2.1 射频功率放大器的研究背景 ......................................... 2 2.2 射频功率放大器的研究意义 ......................................... 3 2.3 国内外研究状况和发展态势 ......................................... 3 2.4 射频功率放大器的参数 ............................................. 6 2.4.1 效率 .......................................................... 7 2.4.2 线性度 ........................................................ 7 2.4.3 杂散与输出噪声 ................................................ 9 3 射频功率放大器的分类与电路结构 ....................................... 10 3.1 A 类功率放大器 .................................................. 11 3.2 B类功率放大器................................................... 12 3.3 AB类功率放大器 ................................................. 13 3.4 C类功率放大器................................................... 13 3.5 D类功率放大器 .................................................. 14

3.5.1 电流开关型 3.5.2 电压开关型

D类功率放大器 ..................................... 15 D类功率放大器 ..................................... 15

3.6 E类射频功率放大器 ............................................... 17 3.6.1 具有并联电容的E类功率放大器 ................................. 17 3.6.2 具有并联电路的E类功率放大器 ................................. 18 4 具有并联电容的E类功率放大器设计 ..................................... 19 4.1 E类射频功率放大器原理分析 ....................................... 19

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宁夏理工学院毕业设计

4.2 E类射频功率放大器设计步骤 ....................................... 21 4.2.1 选择功放管 ................................................... 21 4.2.2 设计输入输出阻抗匹配网络 ..................................... 22 4.2.3 引入差分输入输出结构 ......................................... 25 4.2.4 E类功率放大器电感的设计 ..................................... 26 4.2.5 引入反馈技术 ................................................. 27 结束语 ................................................................. 28 致谢 ................................................................... 29 参考文献 ............................................................... 30

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