本論文提出一種應用於數位D類放大器的高效能三角積方調變器電路。D類放大器較傳統AB類的音頻放大器具有更高效能的優勢，而數位化的D類放大器可以簡化音頻轉換器電路，節省電路面積與功耗。然而傳統D類放大器使用脈衝寬度訊號來實現，除了諧波失真嚴重外，較小的訊號動態範圍造成效能不佳。本論文的D類放大器設計使用三角積分調變技術產生脈衝訊號，用以改善上述缺點。藉由分析兩種不同回授架構的三角積分調變器電路並研究兩者對D類放大器的好壞，本論文提出一個新三角積分調變器電路架構，使之較傳統電路有更廣的動態範圍和更低的諧波失真。經硬體實現驗證顯示，本論文所提的新架構，電路複雜度與傳統架構相仿，而諧波失真較之傳統架構降低了大約10%左右；其調變指數可達100%，大幅改善傳統架構最大輸入振幅受限的缺點。本論文所提的新架構能有效提升電路效能與品質。 A high performance sigma-delta modulator for class-D audio amplifiers is proposed in this thesis. Class-D topology is superior to class-AB one for its higher efficiency. In addition, realizing class-D amplifier by all digital can greatly reduce audio data converter circuits, saving hardware and power consumption. However, the traditional class-D amplifier based on pulse-width modulation suffers from larger harmonic distortions and poor performance caused by limited dynamic range. This research uses sigma-delta modulation techniques to mitigate such drawback. By analyzing two different types of sigma-delta modulator topologies, a new architecture is proposed. The experimental results show that, compared to the conventional class-D sigma-delta modulators, the proposed architecture can improve total harmonic distortions about 10% and can operate with a modulation index of 100% maximum input range, with same hardware complexity.
