USB3.0隨身碟之EMI解析方法與對策

Abstract

本篇論文使用銀燦科技所設計的IS917 USB3.0 NAND Flash Controller搭配上Intel所生產的L85C 20nm MLC PF2916B08LCMFP所組成的USB3.0隨身碟(USB3.0 Flash Drive, UFD)為實驗待測物，探討此高速隨身碟在兩層板的上的電磁干擾(Electromagnetic Interference, EMI)問題，並找出有效方法來抑制電磁干擾的產生。 改善的EMI設計並不是通用法則，其需要有完整的分析程序，並考慮每一個潛在的源頭與路徑且一個一個的解決。降低EMI最有效的方法便是控制信號的分佈路徑與其信號源頭，在現今的電子產品中其電磁干擾最主要是來自於IC中的同步切換雜訊(Simultaneous Switching Noise, SSN)，此雜訊電流能控制好且降低它的輻射能量，必能解決EMI問題。此論文針對EMI雜訊使用了去耦合電容(Decoupling Capacitor)與改善非理想電流迴路(Non-ideal Current Loop)，將832MHz與998MHz降低了24dB與5dB。

This thesis uses USB3.0 Flash Drive (UFD) as an experimental device. This device consists IS917 USB3.0 NAND Flash Controller from Innostor and L85C 20nm MLC PF2916B08LCMFP from Intel to research Electromagnetic Interference (EMI) issue on a 2 layers high speed UFD PCB and also find out the effective method to suppress the EMI noise. There is no common technique to reduce EMI, the way to solve EMI needs a complete analysis procedure and also to consider each noise source and propagation path. The effective method to suppress EMI noise is to control noise source and path. Most of the EMI noises come from Simultaneous Switching Noise (SSN) in the ICs of electronic products at the present time. Controlling this noise current and reducing its radiated energy will overcome the EMI problem. This thesis uses two techniques to reduce EMI noises. One is decoupling capacitor and the other one is improving non-ideal current loop, the final result suppresses 832MHz and 998MHz EMI noise to 24dB and 5dB.