高效音频功率放大器.doc

PAGE 南昌工程学院毕业论文 PAGE 2 - 高效音频功率放大器 音频功率放大器主要有A类、B类、AB类、D类等。D类音频功率放大器与其它类型音频功率放大器相比有效率高的显著优点，故本论文采用的是D类功率放大器。高效率会带来很多的好处，例如延长电池使用时间，发热低，这些优点使其在移动多媒体设备上具有广阔的发展前景。 本文比较了各种类型的音频功率放大器的优缺点，然后重点介绍D类功率放大器的工作原理及其各部分电路选择、分析与计算。功率放大器主要包括的各个模块：三角波产生器、比较器，前置放大器，振荡器，驱动电路，基准电流源，电压反馈环路以及过热，过流，欠压，启动保护电路等进行了设计。 关键词：D类音频功率放大器，脉冲宽度调制，效率 High efficiency Audio power amplifier ABSTRACT：Audio power amplifier mainly include class A class B class AB and class D and so on ,compared with other class audio power amplifier class D audio power amplifier has an such obvious advantage which is high efficiency that we use it for our essay .there’s much benefits with high power such as which can make the battery run much longer, and make the audio power amplifier dissipate less heat, all that make it has a boarded promise on mobile m-medias development. First，the advantages and disadvantages of all kinds audio power amplifier is compared，then the theory of class D audio power amplifier as well as the choice ,analysis and circulation of respective circuit is especially introduced, The circuit includes triangle-wave generator ,amplifier, comparator, oscillation，drive ,current reference, feedback loop,，and voltage loop and thermal protection, over current protection, startup protection . KEY WORD: class D audio power amplifier, pulse width modulation, efficiency 目 录 目 录…………………………………………………………………………………………… 6 第一章：绪论…………………………………………………………………………………..….7 1.1 D类音频功率放大器的研究背景……………………………………………………….7 1.2 D类音频功率放大器的研究意义和现状……………………………………………….7 1.3 D类放大器技术………………………………………………………………………… 8 第二章：方案论证与比较……………………………………………………………………….9 2.1高效率功放类型的选择……………………………………………………………………9 2.2高效D类功率放大器实现电路的选择…………………………………………………..10 2.2.1脉宽调制器（PWM）…………………………………………………………………..10 2.2.2高速开关电路…………………………………………………………………………10 输出方式………………………………………………………………………………10 开关管的选择……………………………………………………. ……… 11 2.2.3滤波器的选择…………………………………………………………………………12 第三章：主要电路工作原理分析与计算…………………………………………..…………13 3.1 D类放大器的工作原理…………………………………………………………………13 3.2 D类功放各部分电