使用多階轉換器之無濾波器D類音頻功率放大器之設計與實現

Design and Implementation of Filterless Class D Audio Power Amplifier Using Multilevel Converter

林冠良(Kuan-Lang Lin)

指導教授 ： 林佑昇

國立暨南國際大學/科技學院/電機工程學系/碩士(2014年)

摘要

高功率效益的Ｄ類放大器近年來逐漸地受到重視，但由於是開關式的操作，Ｄ類放大器的線性度是需要改善的目標，本論文提出兩個音頻放大器架構，還有研究無線生理訊號的傳輸，研究主題主要分成以下三部分：
第一部分，我們設計一個增強型比較器之D類音頻放大器，其基礎架構為運用一增強型放大器作為比較器，作出脈波寬度調變，我們使用脈波寬度調變來降低失真，並提高其整體的線性度。此外亦利用非重疊電路的控制訊號去驅動功率電晶體，避免因為功率電晶體同時導通而產生貫通電流，造成功率消耗及電路損毀。輸出級是由電感、電容、喇叭組成的低通濾波器，用以驅動後級的喇叭負載，使脈波寬度調變訊號還原成原始的類比聲音訊號。
第二部分，我們設計一無濾波器 D類音頻功率放大器設計，在電路架構方面多階信號為基礎，多階架構，多階架構包含了多階轉換器和一個在調變器之後的組合全加器所組成。在此方法中，信號經過脈波寬度調(PWM)變後重新安排配置成幾個時間分段，而且將這些時間分段裡訊號的整合成二進位形式，然後二進位形式被編碼成控制信號給多階轉換器，多階轉換器將會轉換多階信號到擴大機上，取代傳統二階信號。因此，該方法可以應用到D類音頻功率放大器，只要在調變器之前加入一個時序切割加法器，而且可以取代傳統輸出級變成多階轉換器，從而實現無需外部濾波器。
第三部分，我們研究一個生理訊號的無線傳輸，可以無線截取人體心電圖。無線傳輸生理訊號讓使用者使用更加方便，也提高攜帶性。裝置是用藍芽傳輸截取的生理訊號，再經由藍芽的接收裝置顯示在電腦螢幕。

關鍵字

D類音頻功率放大器 ； 無濾波器 ； 多階轉換器 ； 生理訊號

並列摘要

High power efficiency of Class D amplifiers attention in recent years, gradually, it is a switch-mode operation, the linearity of a Class D amplifier is in need of improvement goals. This paper presents two audio power amplifier architecture and study physiological signal of wireless transmission. This thesis can be divided three part：
The first part, we design an Enhanced Comparator Design of PWM Class D Audio Power Amplifier. The basic architecture is use an enhanced operation amplifier as a comparator, making pulse width modulation. We use pulse width modulation to reduce distortion and increase its overall linearity. The non-overlapping circuits circuit is also added to prevent the short circuit by poor wire connection. In addition, to avoid the shoot through current due to both power transistors are switched on at the same time, the dead time control is adopted. The large current induced by the short circuit would destroy the overall system potentially. The output stage is a low pass filter composition of inductance, capacitance and speaker. It can revert pulse width modulation to original analog signal, and drive to latter stage speaker load.
The second part, we design and implementation of filterless Class D audio power amplifier using multilevel converter. The circuit architecture based on multilevel signal. The multilevel architecture is consisted of a multilevel converter and a combined full adder followed by modulator. In this method, pulse width modulation signal is arranged to several time divisions and integrate into a binary form. Then, the binary form is encoded into parallel control signal to the multilevel converter. Multilevel converter will convert multilevel signal to speaker, replace traditional two-stage signal. Therefore, the method can be applied to class D audio power amplifiers. As long as after the modulator is inserted the shift register, the combined full adder and decoder. And with a multilevel converter replaces conventional output stage, so that achieve without external filters.
The third part, we study biomedical signals of wireless transmission, wireless intercepts human ECG. Wireless transmission biomedical signals allows users to use more convenient, but also to improve portability. Devices with Bluetooth transmission intercepted biomedical signals. Receiving device through Bluetooth and then displayed on the computer screen.

並列關鍵字

Class D Audio power Amplifier ； Filterless ； Multilevel Converter ； biomedical signals

參考文獻

I. English part:

[1] K. C. Lee, C. S. Chae, J. Y. Jeon, K. H. Lee, G. H. Cho, “A High-Performance Fast Switching Charge Dump Assisted Class-k Audio Amplifier,” IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS—I: REGULAR PAPERS, vol. 57, no. 6, Jun. 2010

[2] J. Torres, Adrian C. M., Miguel Angel R. G. , Edgar S. S. , “A Low-Power High-PSRR Clock-Free Current-Controlled Class-D Audio Amplifier,” IEEE JOURNAL OF SOLID-STATE CIRCUITS, vol. 46, no. 7, Jul. 2011

[3] Simon C. L, Vincent C. C. Lin, K, Nandhasri, and J. Ngarmnil, “New High-Efficiency 2.5 V/0.45 W RWDM Class-D Audio Amplifier for Portable Consumer Electronics,” IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS—I: REGULAR PAPERS, vol.52, no. 9, Sep. 2005

[4] D. Cartasegna, P. Malcovati, L. Crespi, K. Lee, L. Murukutla, and A. Baschirotto, “An Audio 91-dB THD Third-Order Fully-Differential Class-D Amplifier,” IEEE CONFERENCE PUBLICATIONS, pp.91-94, Sep. 2011