適用于D類音頻功放的動態(tài)遲滯PWM比較器

系統(tǒng)介紹了基于PWM（Pulse Width Modulation）調(diào)制的D類音頻功率放大器的原理及
特點。針對傳統(tǒng)比較器遲滯固定的不足，通過引入兩路電流反饋，設(shè)計了一種新穎的動態(tài)遲滯PWM比較器。同等分辨率下，其抗噪聲能力遠好于傳統(tǒng)的比較器。電路的設(shè)計基于TSMC0.6μm BCD工藝。Spectre仿真結(jié)果表明，在載波以及輸出的不同狀態(tài)下，比較器的遲滯在20 mV與80 mV之間切換，并且其增益高達79 dB，單位增益帶寬大于10 MHz。
關(guān)鍵詞：PWM 調(diào)制；D 類音頻功放；動態(tài)遲滯比較器
A dynamic hysteresis PWM comparator applied to Class D audio amplifier
Jin Jie1，Wu Chuan-xin1，Xu-Ziyou2
（1．School of Mechano-electronic Engineering，Xidian Univ．，Xi′an 710071，China；
2．School of Electronic Engineering，Xidian Univ．，Xi′an 710071，China）
Abstracts：A systematic introduction to principles and advantages of the class D audio amplifier
based on pulse width modulation （PWM） is presented. Considering the disadvantages of the
traditional fixed hysteresis comparator, a novel dynamic hysteresis PWM comparator with two
paths of current feedback is proposed. Compared with traditional comparators, the proposed
circuit has a better anti-noise character at the same resolution ratio. The circuit is designed with
TSMC 0.6μm BCD technology．Cadence Spectre-based simulation shows that the hysteresis
changes between 20 mV and 80 mV according to different states of the carrier and output, while
its gain is up to 79 dB and unity gain bandwidth is greater than 10 MHz.
Keywords: PWM; Class D audio amplifier; dynamic hysteresis comparator.