基于ΣΔ调制的D类放大器系统设计与仿真

摘要

针对传统D类放大器脉宽调制技术引起的电磁干扰问题,将一个5阶低通ΣΔ调制器应用于一种带反馈闭环结构的D类放大器中。通过建立ΣΔ调制D类放大器的非理想模型,考察输出信号的功率谱特性。仿真分析表明,该模型能够有效抑制低频段的噪声和谐波失真,在基带内实现较高的信噪比,应用于D类功放,与传统脉宽调制方式相比,有效地改善电磁干扰性能。%In view of the fact that pulse width modulation may cause electromagnetic interference（EMI） in Class D Amplifier,this article applies a five-order low pass Σ Δ modulator to A class D amplifier with a feedback loop structure.The output signal spectrum properties are studied by establishing a nonideal model of class D amplifier.Simulation results show that this model can reduce the noise and harmonic distortion in low frequency band,achieve higher signal-to-noise ratio in baseband.Its application in the class D amplifiers can improve the electromagnetic interference performance effectively compared with traditional pulse width modulation.