臺灣博碩士論文加值系統

本論文主要採用了常見的多種放大器架構 ，設計並製作一個可商用化之功率輸出25瓦特，頻率響應寬度可達20Hz至20KHz以上之多級高傳真音頻放大器，除了初步的架構規劃外，並在其設計過程中採用電路模擬程式OrCAD 及 ADS Advance design system修改電路中各元件的工作點以得到高效率、低失真、和最佳之溫度穩定等特性。完成整體放大器電腦輔助設計之模擬後，以元件組裝成放大器電路並進行實機量測後以確定此一放大器之實際特性並與電腦模擬之結果作比較，最後此一放大器也實際應用在音響系統中，以確認其實用性。
整體放大器電路架構中包括三級，第一級為主動式負載電路之差動放大器，此級之架構主要是使用電晶體作為主動式負載並使用其可提供近似開路之高負載特性，來提高電壓放大器之電壓增益，並可避免傳統雙載子電晶體A類放大器設計時為取得最佳直流最佳工作點，需考量電晶體特性曲線以決定集極負載電阻值，然而此種設計會限制射極放大器之電壓增益特性，但主動式負載基本上是以電流鏡作為負載，除了提供偏壓工作點之所需集極電流，也同時維持較大之等效負載阻抗。第二級則為單端集極放大器，使用主動式電流鏡負載，第三級為功率放大器，在設計上必須考慮其效率及溫度效應，因此通常以較高效率之B類放大方式組成，在音頻放大器為避免失真因此大多再採用互補式架構，這種方式提供了功率放大器之較佳效率考量及全波放大，但由於電晶體的障壁電壓會造成放大訊號正負半週期間之交越失真，為了改善此一現象，通常將電路設計改成AB類，並對基極與射極間施加特定數值之直流靜態偏壓以改善交越失真現象。但當電晶體在高功率輸出時，其半導體的接面溫度亦隨之上升而影響電晶體的電壓電流特性，惡性循環的結果甚至造成永久性損害。因此本文採用溫度負回授方式補償以改善此一現象。由模擬程式確認設計的可行性後，實際電路實驗之量測結果可明顯觀察到其改善.模擬與實驗量測結果大致吻合，實機量測輸出功率可達27瓦特，頻率響應之3dB頻寬為10Hz至35KHz，至於溫度補償偏壓係數在電晶體工作範圍內為 -7mv/0C，特性符合設計值，將來應可應用在商品化考量之實用設計架構。

This thesis adopts a variety of amplifier structures in textbooks to design and construct a multi-stage, high fidelity audio amplifier. After the initial framework project plan has been done, we used the commercial circuit simulators ORCAD and Advance design system (ADS) to verify the preliminary amplifier design and modify the circuit operating points of transistors in order to obtain the desired amplifier’s characteristics such as high efficiency, low distortion and the best temperature stability. After the computer-aided design simulation of the overall amplifier is completed we assemble the practical components on the PCB according to the design that is obtained from the simulation to fabricate a prototype of the audio amplifier. And then, we go through the several measurements to make sure the properties of the amplifier. The measurement results show the practical amplifier do satisfied the required specifications and very close to the computer simulation results. Eventually, the amplifier is practically applied in the audio system for ensuring its performance.
The overall amplifier circuit architecture includes three stage amplifiers. The first stage is an active-load differential amplifier that mainly uses transistors as active loading ,which can provide an effective loading close to-open-circuit and to raise the voltage gain and avoid the traditional bipolar transistor class A amplifier design that cannot uses high impedance loading for the consideration of the requirement of the appropriate operation point. The second stage of the amplifier is a single-ended amplifier that is still use a current mirror as the active load to enhance the voltage gain. The third stage design is a power stage, so that we should take the power efficiency and the temperature effects into consideration. Usually, a high efficiency class B amplifier structure is selected. However, the class B amplifier must consider the effect of crossover distortion, therefore the complementary feature with Class AB biasing condition are chosen as the final feature for final stage of the audio amplifier. So that this approach can provide better power amplifier efficiency, and eliminate the crossover distortion. While transistors are processing for providing high power output, their semi-conductor junction temperature will rise and affect the voltage-current characteristics of the transistor, and the vicious cycle can even causes the permanent damage of the transistors. So we intend to adopt a manner that can provide a negative feedback to compensate temperature effect in the practical circuit. The temperature compensation circuit is confirmed their feasibility in the computer simulation and then we could observe the improvement of the temperature stability in the practical measurement results. The good properties of the experimental prototype shown in measurement results could show the promise the amplifier in the future commodity applications.

目 錄
指導教授推薦書
論文口試委員會審定書
長庚大學授權書 iii
誌謝 iv
中文摘要 v
英文摘要 vii
目錄 x
圖目錄 xii
表目錄 xiv
第一章 緒論 1
1.1 研究動機 1
1.2 實驗方法 2
1.3 章節概要 6
第二章 音頻功率放大器基本電路結構及原理 7
2.1 簡介 7
2.2聲音頻率放大器基本理論 7
2.3 AB類放大電路基本架構 8
第三章 音頻功率放大器特性補償電路分析 13
3.1輸入級特性阻抗匹配電路及電壓增益放大電路結構 13
3.2主動式偏壓調整及溫度補償直流偏壓倍增電路 17
3.3偏壓倍增電路 18
3.4溫度補償 19
第四章 電路實驗設計實作程式模擬與儀器量測 20
4.1電路實驗設計實作 20
4.2電路結構設計與交流信號放大流程分析 24
4.3程式模擬與儀器量測 26
4.4程式模擬OrCAD與儀器量測結果比對分析 35
4.4.1直流偏壓點分析 36
4.4.2交流暫態分析 37
4.4.3交流掃描頻率響應分析 38
4.4.4 AB類功率放大級直流偏壓分析 39
第五章 結論 40
參考文獻 41

圖目錄
圖1.2.1儀器量測接線圖 5
圖2.3.1聲音功率放大器電路組成架構 8
圖2.3.2基本電壓放大電路 9
圖2.3.3 B類共射極(CE)放大電路 10
圖2.3.4 B類放大電路直流偏壓工作點 11
圖2.3.5 AB類放大電路直流偏壓工作點 12
圖3.1.1 差動放大器基本結構 14
圖3.1.2 差動放大器主動式負載電路 15
圖3.2.1偏壓倍增器溫度補償電路 18
圖3.2.2 電晶體 VBE(on)溫度特性曲線 19
圖4.1.1 實驗電路基本結構 20
圖4.1.2 實驗電路圖 21
圖4.1.3 實驗電路板銅箔圖 21
圖4.1.4 實驗電路實裝基板(上視圖) 23
圖4.1.5 實驗電路實裝基板(正視圖) 23
圖4.1.6 實驗電路實裝基板溫度耦合傳導結構 24
圖4.3.1暫態模擬輸出波形圖 28
圖4.3.2 暫態模擬輸入端波形圖 28
圖4.3.3 頻率響應曲線 30
圖4.3.4 閉迴路常溫輸入輸出間相移曲線 31
圖4.3.5 閉迴路溫度變化輸入輸出間相移曲線 32
圖4.3.6 開迴路常溫輸入輸出間相移曲線 32
圖4.3.7 輸入輸出間相移與溫度曲線 33
圖4.3.8 Class AB直流偏壓溫度關係 34
圖4.4.1 Q17 直流偏壓 37
圖4.4.2 Class AB直流偏壓溫度補償傳導 39

表目錄
表4.1.1 實驗電路零件構成表 22
表4.3.1 實驗儀器量測設備表 26
表4.3.2 實程式模擬與儀器量測項目比對表 26
表4.3.3 直流偏壓儀器量測 27
表4.3.4 暫態反應輸入輸出儀器量測 29
表4.3.5 頻率增益關係表 30
表4.3.6 直流偏壓溫度關係-儀器量測 34
表4.4.1 程式模擬OrCAD與儀器量測結果比對 35
表4.4.2 Q16，Q17 DC Bias參數 36

參考文獻
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