车联网系统中语音电路EMI滤波设计和优化  

Design and optimization of EMI filtering for speech circuit in vehicle network system

作　　者：李静元 LI Jingyuan(Shaanxi Normal University,Xi’an 710119,China)

机构地区：[1]陕西师范大学

出　　处：《现代电子技术》2019年第18期14-17,21,共5页Modern Electronics Technique

摘　　要：针对车联网语音系统电磁辐射超标的问题,提出一种基于开关信号传输的EMI滤波方案设计与优化.通过实测结果分析超频点产生的原因,最终定位在语音芯片内部D类放大器和电路板上开关电源的传导辐射上,据此对原理图进行改进优化,增加对共模噪声和差模噪声滤波网络设计,从供电源头抑制噪声传导干扰,语音电路的D类放大器产生的噪声利用π型网络二次滤波后大大降低了噪声强度.改进后的方案按照车载标准复测后通过测试且有足够的余量,提高了车载系统的可靠性.In allusion to the problem of electromagnetic radiation exceeding standard in the vehicle network speech system,a design and optimization of EMI filtering scheme based on switching signal transmission is proposed. The causes for pro- ducing the overfrequency points are analyzed with actual measured results,which are located to the conduction radiation of the class D amplifier inside the speech chip and the switching power supply on circuit board. According to it,the schematic diagram is improved and optimized,and the common mode noise and differential mode noise filtering network is designed to suppress the noise conduction interference at the source of power supply. The intensity of the noise generated by the D class amplifier in the speech circuit is greatly reduced by the means of the second filtering of PI network. The improved scheme was retested according to the vehicle standard and passed the retest. The result indicates that it has enough redundancy,improves the reliability of the vehicle-mounted system.

关 键 词：车联网 滤波设计 EMI优化 滤波优化 噪声传导 复测验证 

分 类 号：TN409.34[电子电信—微电子学与固体电子学]