摘 要

在音頻功率放大器的市場上，AB類一直處于統(tǒng)治地位。近年來，隨著MP3、DVD和移動電話等便攜式消費電子產品的普及，D類音頻功率放大器以高效率、低功耗、小體積的優(yōu)點日益成為音響領域的主流，在未來便攜式和大功率音頻視頻領域中將具有廣闊的發(fā)展前景，因此對高效音頻功率放大器的設計具有十分重要的意義。
本設計根據D類放大器的工作原理設計的D類音頻功率放大器，能對音頻信號進行放大，放大器的通頻帶達到300~3400HZ，輸出功率1W，輸出信號無明顯失真。根據D類功放的原理分別設計了前置放大模塊、三角波產生模塊、比較器模塊、驅動模塊、H橋互補對稱輸出及低通濾波模塊等。其中三角波產生器及比較器共同組成脈寬調制（PWM）模塊，H橋互補對稱輸出電路采用驅動電流小、低導通電阻及良好開關特性的VMOSFET管，濾波器采用兩個相同的四階Butterworth低通濾波器。


關鍵詞：高效，音頻，D類功放，放大器


Abstract
In the audio amplifier market. AB has been the dominant class. In recent years, along with MP3，DVD and mobile phones, the popularity of portable consumer electronic products, D audio power amplifier with high efficiency, low power, small size advantage of the field is increasingly becoming the mainstream audio, portable and high-power audio in the future Video area will have a bright future. Therefore, efficient audio power amplifier design is of great significance.
According to the working principle of class D amplifier, this product is designed and the audio signal can be amplified to the amplifier’s pass band to 300 ~ 3400 HZ, the output power 1W, the output without significant distortion. Class D amplifier according to the principle of preamp modules were designed, triangular wave generator module, comparison module, driver module, H bridge output and the complementary symmetric low-power filter module. One triangular wave generator and pulse width modulation comparator common form (PWM) module, H bridge output circuit using complementary symmetry drive current, low resistance and good switching characteristics of VMOSFET tube, filter uses two identical fourth-order Butterworth low-pass filter.
KEY WORDS: High-Efficient, Audio, Class D amplifier, Amplifier

目 錄
1 緒論 ................................................................................................1
1.1 音頻功率放大器概述 ................................................................1
1.2 D類音頻功率放大器的發(fā)展現狀 ................................................................2
1.3 本論文主要內容 ................................................................................3
2 音頻功率放大器 ................................................................................4
2.1 音頻功率放大器的指標 ................................................................4
2.1.1 THD+N指標 ................................................................................4
2.1.2 功率放大器的效率η ................................................................4
2.1.3 最大輸出功率（POCM） ................................................................4
2.1.4 脈沖寬度調制（PWM） ................................................................5
2.1.5 轉換速率 ................................................................................6
2.2 功率放大器的分類 ................................................................................6
2.2.1 A類放大器 ................................................................................6
2.2.2 B類放大器 ................................................................................7
2.2.3 AB類放大器 ................................................................................8
2.2.3 D類放大器 ................................................................................8
2.2.4 T類放大器 ................................................................................9
2.3音頻功放的主要技術指標 ................................................................9
3 D類功率放大器 ................................................................................11
3.1 D類放大器原理 ................................................................................11
3.2 D類放大器的系統(tǒng)分析 ................................................................12
3.3 綜合比較 ................................................................................13
4 D類音頻功率放大器的設計 ................................................................14
4.1設計任務與要求 ................................................................................14
4.1.1 設計任務 ................................................................................14
4.1.2 設計要求 ................................................................................14
4．2方案論證與比較 ................................................................................14
4.2.1 脈寬調制器（PWM） ................................................................14
4.2.2 高速開關電路 ................................................................................15..