防破音D类音频功放的设计与应用

随着多媒体便携设备的普及,音频功放已经成为音频部分的标准配置,D类功放以其高品质高效的特点得到了越来越广泛的应用。在便携产品中,音频功放由于输入音乐信号过大或者电源电压过低,会产生削顶失真。采用防破音技术,可以通过自动增益调节技术来提供一个完美的解决方案。文章介绍了常见的防破音技术,提出了一种改进的AGC(自动增益控制)技术在D类功放中的设计与应用。改进的AGC技术通过对PWM输出的采样来判断失真程度,依据失真程度用防破音电路产生的PWM波形来自动调节运放增益,实现最大功率的无失真输出。

Design and Application of Non-clip Class-D Audio Power Amplifier

With the popularization of multi-media portable devices, audio power amplifier has become a basic component of audio part. Class-D audio power amplifier is widely used because of its high efficiency and excellent characteristics. In portable devices, audio power amplifier will produce clipping distortion when the input music signal is over level or the voltage of battery is low. Non-clip technology will provide a perfect solution with automatic gain control. This paper analyzed the common Non-clip technology, and proposed the design and application of an improved AGC method in Class-D amplifier. The improved AGC method detects the distortion of output PWM signal, and automatically control the gain by the PWM waveform modulated by the Non-clip circuit, eventually realized the maximum output power without distortion.