In this article, acoustic noise of printed circuit board (PCB) introduced by multilayer ceramic capacitors (MLCCs) on power distribution network (PDN) is studied. The correlation of PDN power rail noise, MLCCs and PCB dynamic characteristics, and PCB acoustic noise is demonstrated on a real mobile product through electrical, vibrational, and acoustic measurements. Two measurement methodologies are proposed to identify the problematic MLCCs on the power rail. One method analyzes the board and MLCCs vibration properties with the external electrical signal applied on the power rail on a product board. Other measurement detects the problematic MLCCs based on the coherence value between the power rail signal during product operation and MLCC vibration characteristics. By replacing the identified original MLCCs with low acoustic noise ones, the PCB vibration is clearly reduced. With the MLCCs’ influence on PCB vibration studied, a measurement methodology is also proposed to analyze the PCB intrinsic vibration properties. The intrinsic modal response of PCB is applied to predict the MLCC-induced PCB vibration. The obtained modal response can also provide design guidelines for MLCC placement to reduce the level of PCB vibration.

中文翻译：

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移动系统配电网多层陶瓷电容器声噪声测量方法

本文研究了多层陶瓷电容器 (MLCC) 在配电网络 (PDN) 上引入的印刷电路板 (PCB) 噪声。PDN 电源轨噪声、MLCC 和 PCB 动态特性以及 PCB 声学噪声的相关性通过电气、振动和声学测量在真实的移动产品上得到证明。提出了两种测量方法来识别电源轨上有问题的 MLCC。一种方法是利用施加在产品电路板上电源轨上的外部电信号来分析电路板和 MLCC 的振动特性。其他测量根据产品运行期间的电源轨信号与 MLCC 振动特性之间的相干值来检测有问题的 MLCC。通过用低噪声的MLCC替换已识别的原始MLCC，PCB 振动明显减少。通过研究 MLCC 对 PCB 振动的影响，还提出了一种测量方法来分析 PCB 的固有振动特性。PCB 的固有模态响应用于预测 MLCC 引起的 PCB 振动。获得的模态响应还可以为 MLCC 放置提供设计指南，以降低 PCB 振动水平。