雙聲道D類音頻功率放大器之差頻消除電路設計

The Beat Frequency Cancellation Circuit Design of Dual Channel Class D Audio Power Amplifier

汪信宏(Hsin-Hung Wang)

指導教授 ： 饒建奇

淡江大學/工學院/電機工程學系碩士在職專班/碩士(2012年)

https://doi.org/10.6846/TKU.2012.00359

摘要

音頻功率放大器對於一個音響系統扮演著很重要的角色。但若以功率效益方面來比較，D類功率放大器有較優越的輸出功率表現。對於理想的D類功率放大器而言,它的最大效率理論上是可達到90%甚至100%。 採用自激振盪調制方式的Class D音頻功率放大器IC晶片內部電路設計成可使用在兩個或多個獨立的音效聲道上，在兩聲道功率輸出 PWM 方波訊號會有震盪頻率非同步的情況發生，而產生出所謂差頻的現象，假使其聲音頻率差距在人耳周波數的範圍內，此時IC工作在無音源信號輸出下，就會很容易產生這樣的差頻聲音，雖然聲音微弱但也會很清楚的被人耳所聽到，而造成IC使用上的困擾。 而為了解決這樣的問題，本論文針對雙聲道Class D音頻功率放大器所產生出來的差頻問題而設計出的應用測試電路來做其探討和研究。

關鍵字

放大器 ； 自激 ； 全橋式

並列摘要

Audio power amplifiers play an important role in the audio system.Compared by power efficiency,Class-D power amplifiers have better performance.The theoretical maximum efficiency of Class-D designs is 100%,and over 90% is attainable in practice.
Use the self-oscillation Class D audio power amplifiers IC chip's internal circuit is designed to be used on dual or several multi independent audio channel, and when dual audio channel transmit output power,PWM signal osc frequency is nonsynchronous and result the Beat Frequency. If the difference of sound frequency is within the range for ear's frequency, IC work tends to occur the situation of the Beat Frequency when there is no sound source's signal output at this time.
Although the sound is weak, people can still hear it clearly and which will cause persecution when using IC.In order to solve such problem, this theory is aimed at the problem of the Beat Frequency which is caused from dual audio channel Class D and designs the applied test circuit for discuss and study.

並列關鍵字

Class D ； PWM

參考文獻

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