音頻放大器設計與實現

Abstract

本論文提供一個音頻電路的設計方法，以具有錄/放音功能的語音晶片為範例，先定出規格，再依此目標進行設計，實現一個實用的音頻電路，將重點放在設計的方法與步驟，並評估電路的音效性能指標。 首先說明前置放大器、濾波電路與功率放大器設計方法與步驟，以及聲音訊號輸入源、輸出揚聲器介紹。以範例說明如何設計完整音頻放大器系統，藉由電路模擬軟體PSpice模擬電路，實際量測驗証實體電路，電路量測由Tektronix TDS2002示波器和數學軟體Matlab 7.0來完成。 此外，針對頻率響應、頻譜分析、總諧波失真、訊號雜訊比、效率的模擬結果與量測結果進行比較，最後，以PCB實際完成電路操作與量測。

A method to design an audio circuit is presented,and a voice chip with record/play is an example. The standard is set and the design proceeds with it. To realize a useful audio circuit,the emphasis is put on the methods and flow to design it.The performance indicators are also evaluated. At first,the design method and flow to design the preamplifier , the filter circuit and the power amplifier are mentioned. Besides,the audio signal input and the output speaker are introduced.There are examples to explain how to design an complete audio amplifier system and it is simulated by circuit simulation software ,PSpice. The realized circuit is measured with oscilloscope Tektronix TDS2002 and mathematic software Matlab 7.0. The results of simulation and measure about the frequency response,frequency spectrum analysis,total harmonic distortion,signal/noise ratio and efficiency,are compared. Finally,the circuit is realized.