D类功放中数字调制器的研究与实现

数字脉冲宽度调制(Digital Pulse Width Modulation,DPWM)结构简单、稳定性好,是主动声呐D类功放中常用的调制技术,但是它会产生信号失真和电磁干扰问题。针对主动声呐中D类功放的要求,设计了一种新的1.5bitΣ-Δ调制器。该调制器不仅能够改善DPWM存在的信号失真和电磁干扰问题,而且能够解决常规Σ-Δ调制器存在的高开关频率导致的高开关损耗问题。采用现场可编程逻辑门阵列(FPGA)对该调制器进行实现,在全桥D类功放上进行了实验验证。通过1.5bitΣ-Δ调制器和DPWM性能对比,表明该1.5bitΣ-Δ调制器适合主动声呐D类功放的应用。

Research and implementation of digital modulator in underwater acoustic power amplifier

Digital pulse width modulation with simple structure and excellent stability is commonly used in active sonar class D power amplifier. However there exist problems about distortion and electromagnetic interference（EMI）. Counting for the need of active sonar class D power amplifier, a new 1.5 bit Σ-Δ modulator is proposed. This modulator is not only capable of improving distortion and EMI existing in DPWM, but also can solve the problem of high switch losses caused by high switch frequency of conventional Σ-Δ modulation. The modulator is successfully implemented in FPGA and has been tested and verified on the platform of full bridge class D power amplifier. Through the comparative analysis between 1.5 bit Σ-Δ modulation and DPWM, it is concluded that the proposed modulator is suitable for active sonar class D power amplifier.