摘要：随着MP3、移动电话等便携式消费电子产品的普及，D类音频功率放大器以高效率、低功耗、小体积的优点日益成为音响领域的主流，因此D类音频功率放大器的设计具有十分重要的意义。

本文设计了带有啸叫抑制功能的D类音频功率放大器，根据D类功放的原理分别设计了前置放大模块、脉宽调制模块、驱动模块、H桥互补对称输出模块、低通滤波模块以及啸叫检测与抑制模块等。其中脉宽调制（PWM）模块由三角波产生器及比较器共同组成。啸叫检测与抑制模块由单片机STM32和LTC1068程控陷波器等元件组成。该设计能够实现对音频信号无明显失真地放大，还能对啸叫进行检测并抑制。65884

毕业论文关键词：D类音频功率放大器，脉宽调制，单片机，啸叫抑制

Abstract:With the popularity of MP3, mobile phones and other portable electronic products, the class D audio power amplifier has increasingly become the mainstream of the sound field with the advantages of high efficiency, low power consumption and small size . Therefore, the design of the class D audio power amplifier has very important significance.

The class D audio power amplifier is designed in this paper with the function of howling suppression. According to the principle of class D power amplifier,some modules are successfully designed by me ,such as the front amplifier module, PWM module, driver module, H bridge complementary symmetrical output module, lowpass filter module, howling detection and suppression module etc.The pulse width modulation (PWM) module is composed of triangular wave generator and comparator.Howling detection and suppression module is made up of MCU STM32 and programmable LTC1068 notch component. The design can amplify the audio signal without significant distortion.At the same time, it also can detect and suppress howling.

Keywords: D class audio power amplifier, PWM, SCM, howling suppression

目  录

1 前言 4

1.2 D类音频功率放大器的发展 5

2 音频功率放大器 6

2.1 音频功率放大器的主要指标 6

2.1.1 THD+N指标 6

2.2 D类放大器原理 6

2.3 D类放大器的指标分析 8

3 D类音频功率放大器的设计 10

3.1 D类功率放大器的组成结构 10

3.2各单元电路的设计 10

3.3 D类音频功率放大器的总体结构电路 16

4 系统模块仿真测试 17

4.1前置放大电路 17

4.2 比较器电路 18

4.3 H桥互补对称输出及低通滤波电路 19

4.4供电电源电路 20

5 啸叫抑制 21

5.1 啸叫产生的原理 21

5.2 啸叫的危害 22

5.3 啸叫抑制的常用方法 22

5.4 啸叫抑制模块设计 23

5.4.1 系统框图 23

5.4.2 啸叫抑制流程图 24

5.4.3 系统设计 24

结论