三角積分調變器與D類音頻放大器設計

Abstract

本論文討論了三角積分調變器的數位及類比兩種應用，前者可應用在數位類比轉換器以及非整數除頻器上；後者可應用在類比數位轉換器、直流-直流電壓轉換器及切換式功率放大器上。最後依據數位及類比的應用，設計了應用在非整數除頻器以及非線性切換式功率放大器之兩種三角積分調變器。 藉由應用非整數除頻器在非整數頻率合成器上，可以減少鎖定時間及縮短通道頻率間距。本論文設計一個採用預先進位加法器實現的數位MASH 1-1-1架構，可配合多除數除頻器達到非整數除頻的效果。 非線性放大器已經被大量應用在手持式行動裝置的音頻放大器上，最明顯的好處在於功率效能高，能提升電池使用時間，降低熱損耗。然而相較於線性放大器來說，總諧波失真較高，因此只能應用在對音質要求較低的音頻系統。本論文設計一個三階的類比三角積分調變器，完成音頻D類放大器整體系統模擬。

Applications of the delta-sigma modulator in digital and analog circuits are discussed in this thesis. Delta sigma modulator can be used in digital circuits such as digital-to-analog converters and fraction-N frequency synthesizers; or in analog circuits such as analog-to-digital converters, DC-DC converters and switched-mode power amplifiers. According to these applications, a digital modulator for fractional divider and an analog modulator for nonlinear switched-mode power amplifier are proposed in the thesis. We can decrease locking time and reduce channel bandwidth by applying fractional divider in fractional-N frequency synthesizers. Therefore, a digital MASH 1-1-1 modulator based on the carry-look-ahead adder which can integrate with multi-modulus divider to realize the fractional division function is designed and presented in this thesis. Class-D power amplifiers have been widely used as the audio amplifiers in portable devices. The greatest advantage is the high power efficiency of this kind of amplifier, which can improve the operating time and lower the heat dissipation. Nevertheless, the total harmonic distortion in nonlinear amplifiers is much higher than the linear ones. Therefore, the applications of the nonlinear amplifiers are limited to lower-quality audio systems. A class-D audio amplifier system based on a third-ordered analog delta-sigma is proposed and designed in this thesis.