D类音频功放具有高效、节能、小型化的优点，广泛应用于便携式产品、家庭AV设备及汽车音响等多个领域。文章设计了一款工作于5V电源电压并采用PWM来实现的D类音频功率放大器，整个系统包含了输入放大级、误差放大器、比较器、内部振荡电路、驱动电路、全桥开关电路及基准电路。通过引入反馈技术来减小系统的THD指数，采用双路反宽调制方案不仅抑制了D类音频功率放大器的静态功耗，而且达到了去除D类音频功率放大器输出端低通滤波器的目的，减小了系统的体积。

With the advantages of high efficiency, energy saving and small size, the class D amplifier is used extensively in portable applications, home AV equipment, car audio and so on. In this paper, the Class D audio power amplifier with PWM and 5V supply is presented. The entire circuit contains a preamplifier, an error amplifier, comparators, oscillator, gate-driver circuit, full-bridge, and reference circuit. Feedback is applied to reduce the total harmonic distortion. A dual PWM scheme is used to minimize static power consumption of the system, and it also removes the LPF, makes the system smaller.