D 類放大器藉由切換開關的方式可達到卓越的功率效率，因此被廣泛應用於各種 音頻應用，然而輸出級的切換開關操作不可避免地產生了電磁干擾，採用 CMFBD 調 變是降低共模電磁干擾有效的方法，但是其在小輸入時會產生窄波，將於低輸出功率範圍顯著地增加總諧波失真加雜訊。本論文針對類比輸入閉迴路架構的 D 類放大器，提出一個應用於 CMFBD 輸出級的窄波消除技術，此外，本論文亦採用具三電平前饋路徑之頻率等化脈寬調變殘餘混疊失真抑制技術，因此，在整體輸出功率範圍下總諧波失真加雜訊可被大幅減少，同時兼具良好的共模電磁干擾抑制效果。
本論文之 D 類放大器晶片實現於 TSMC 0.18 微米技術，由 pre-layout 模擬結果顯示，本論文在 5 伏特之電源電壓及 8 歐姆負載下可達到 0.00075%之最低總諧波失真加雜訊且僅消耗 1.1 毫安培之靜態電流，此外，在使用所提出之窄波消除技術下，動態範圍及低輸出功率範圍之總諧波失真加雜訊皆可大幅改善達 15 dB。與現有最佳文獻之 D 類音頻放大器相比，可達具競爭力之動態範圍 107 dB。

Class-D amplifiers are widely used in various audio applications since they achieve superior power conversion efficiency by their switching behavior. However, the presence of switching activity at the output stage inevitably generates electromagnetic interference (EMI). Adopting common-mode-free BD (CMFBD) modulation is an effective way to reduce common-mode (CM) EMI, but it produces narrow pulses when a small input is applied, significantly increasing the total harmonic distortion plus noise (THD+N) in the low output power (POUT) range. In this thesis, a narrow pulse elimination (NPE) technique for the CMFBD output stage is presented for analog-input closed-loop Class-D audio amplifiers. Furthermore, the frequency-equalized PWM-residual-aliasing reduction technique with a tri-level feedforward path is also adopted. Therefore, the THD+N over the entire POUT range can be greatly reduced with a well-suppressed CM EMI.
Implemented in the TSMC 0.18-μm process, the pre-layout simulation shows that this work’s Class-D amplifier achieves the minimal THD+N of 0.00075% while consuming a low quiescent current of 1.1 mA with a supply of 5 V and a speaker load of 8 Ω. In addition, with the presented NPE technique, both the dynamic range and the THD+N in the low POUT range are greatly reduced by 15 dB. Compared with state-of-the-art Class-D audio amplifiers, this work features the competitive dynamic range of 107 dB.

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