D类放大器在防空数字电声警报器中的应用

Application of D class amplifier in acoustic alarm of civil air defense

阐述了防空数字电声警报器中大功率D类放大器的构成、原理、效率及其应用问题。D类放大器要放大的信号是经过调制的脉冲宽度信号即PWM信号。音频信号(警报信号)的幅度只是用来调制脉冲载波信号的宽度,功率放大器完全处于开关状态,大幅度减少功率输出器件的自身功耗。采用场效应管(NMOSFET)的全桥结构+巴特沃特低通滤波器的架构,实现了大功率、超大功率的警报信号功率要求,解决了D类放大器在防空电声警报器中应用的难题,在生产中达到了警报功率输出效率93%～95%。在正弦信号输出时效率达到90%。这样的高效率是AB类模拟大功率放大器输出功率无法比拟的,使防空警报器实现了整体数字化。

This paper elaborates the composition, principle, efficiency and application problems of D class amplifier. The signal enlarged by D class amplifier is a pulse width modulation signal namely PWM signal. Audio signal （warning signals） is used to modulate the range of the pulse width of the carrier signal, the power amplifier is completely in switch state, thus greatly reducing the power loss of output device. The MOSFET whole bridge structure ＋ bart walter low-pass filter framework is used to realize high power or super power warning signal, which solves the application of the class D amplifier. In production the efficiency reaches 93 %-95 %, while in sine signal output it reaches 90%. Such efficiency is beyond that of AB kind of amplifiers, realizing whole digital alarm.