100W的D类功率放大器的设计

文档编号:DQ077   文档字数:10637,页数:24

摘  要

 本文设计了一种以100W功率放大器为核心的D类功率放大器。本设计采用全桥改进PWM方案实现的D类放大器具有效率高、降低滤波器要求等特点。采用CPLD实现改进的全桥PWM方案，并结合DSP实现串并转换、数字插值和噪声整形等处理，可实现高保真的音频放大器。设计的数字功率放大器可对数字音源输出的音频信号进行直接放大，为数字音源和功率放大的整合提供了完整的解决方案。它改进了PWM方案，输出开关管采用高速MOSFET管，连接成互补对称H桥式结构，平均效率可达到85%左右，兼有输出1：1双变单电路，噪声和干扰的屏蔽方法，此外还有输出短路保护。其工作原理为：输入信号与三角波信号在通过比较器比较之后，产生一个脉冲信号，送至前置放大电路，再经过低通滤波器滤波，以保证输出信号在一定的带宽内。D类放大器之所以能实现这样的效率，是因为D类放大器与开关模式电源的工作方式相似，其中输出MOSFET要么是完全启动(饱和)，要么是完全关闭(切断)的。因而可以减小晶体管的功率损耗，增加放大器的效率。
 
关键词：D类功率放大；改进PWM方案；短路保护；干扰屏蔽

Abstract
 The designed D class amplification has characterized of improver full PWM program high efficiency and lower filter requirements. CPLD realization of adopted full-bridge PWM improvement program, and combined with the realization by DSP SERDES, digital interpolation and noise shaping processing, etc., can be realized by high-fidelity audio amplifier. Digital power amplifier designed for digital audio output to the audio signal directly to amplification, digital sound and power was amplified to provide a complete integrated solution. It has been improved PWM program, the output pipe by using high-speed switching MOSFET tubes, are connected into a complementary symmetric H-bridge structure, the average efficiency of around 85% can be achieved by the combination of 1:1 two-change single-output circuits, noise and interference by shielding methods, in addition to short-circuit protected output. Its working principle is: the input signal with the triangular wave signal is compared by comparing the device after a pulsed signal to the preamp circuit, and then, after filtering low-pass filter to ensure that the output .signal within a certain bandwidth. Class D amplifiers can achieve this because of efficiency, because the D-type switch-mode power amplifier with the work, which is similar or the output MOSFET is fully activated (saturated), or is completely closed (cut off) of the. Transistors can be reduced and thus the power loss and increase efficiency by amplifier.

Key Words: D class power amplification；Programs to improve the PWM ；pulse-width modulation；current overload protection；

摘要.…………………………………………………………………..………….…..Ⅰ
英文摘要………………………………………………………………………….…...Ⅱ
绪论……………………………………………………………….……………….…1
 1.1  前言…………………………………………………………………………..…….……..1
 1.2  D类功率放大器目前水平……………………………………………………………….2
第二章  D类放大器的放大电路设计……………………………………………….……3
 2.1  D类放大器的基本结构………………………………………………………………….3
 2.2  D类放大器的设计思路………………………………………………………………….4
    2.2.1 基本设计方案……………………………………………………………………….4
 2.3  D类放大器的工作原理………………………………………………………………….7
 2.4 宽带调制（PWM）………………………………………………………………………..11
 2.5 改进全桥PWM方案的模拟实现方法……………………………………………….…..12
 2.6改进全桥PWM方案的数字实现方法……………………………………………………13
第三章 其他辅助电路设……………………………………………………………………..14
  3.1 短路保护电路…………………………………………………………………………...…14
 3.2 噪声和干扰屏蔽设计…………………………………………………….…….……….....15
 3.2.1噪声和干扰………………………………………………………………..………..15
 3.2.2  屏蔽的基本原理………………………………………………...…….….………15
第四章 进一步改进措施…………………………………………………………..…..…….17
 4.1尽量减少静态功耗和动态功耗………………………………………………..………….17
第五章 总结……………………………………………………………………………………18
参考文献…………………………………………………………………………..…..……......19
致谢………………………………………………………………………………………………20
附录……………………………………………………………………………….……………...21

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