USB3.0與WiFi2.4 裝置間之電磁干擾分析與解決方案

Analysis and Solution for the Interference Between Co-existing USB 3.0 and 2.4 GHz WiFi Devices

卓駿達(Chun-Ta Cho)

指導教授 ： 吳霖堃

國立交通大學/電機學院/電信工程系所/碩士(2017年)

摘要

本論文針對USB3.0訊號干擾WiFi無線網路導致其資料傳輸吞吐量降低的問題進行分析並提出解決方式。藉由量測無線網路資料傳輸吞吐量與距離相對關係(Rate vs Range,簡稱RvR)發現USB3.0訊號干擾2.4GH 之WiFi頻帶接收訊號問題，本論文亦分析不同對策。
針對接收訊號干擾問題，先以天線接收靈敏度(Rx sensitivity)與傳導式接收靈敏度比較因而找出有問題之天線。主要解決辦法係以遮蔽隔離USB3.0輻射干擾訊號，如使用吸波材遮罩USB3.0連接器及走線。但基於生產方便性的考量，最後我們以更改高速傳輸線走線方式將其改置於PCB板內層以利用金屬接地層的屏蔽特性解決此干擾問題，使得WiFi無線網路資料傳輸達規格要求，同時USB3.0亦可正常作動。

關鍵字

電磁干擾 ； 介面 ； 技術指標 ； 網際網路 ； 差動訊號

並列摘要

In this thesis, USB3.0 signal interfering with WiFi wireless network causing degradation in data transmission performance is analyzed and several solutions are proposed. By measuring throughput Rate versus Range (RvR), the problem of USB3.0 signal interfering with the receiver of 2.4GH WiFi device is found.
At first,antenna air sensitivity is measured and compared with the conduction receiver sensitivity to find the antenna that picks up the interfering signal. The main solution is to use shield to isolate USB3.0 radiation interference signals, such as the use of absorber to cover USB3.0 connector and routing trace. However, considering the ease of production, the final solution adopted is to relocate the high-speed transmission line from layer 1 into layer 3 of the 4-layer PCB board which uses the inherent shielding property of the intervening metal ground plane to solve this interference problem.

並列關鍵字

USB3.0 ； WiFi ； EMI ； IEEE802.11

參考文獻

[1] D. G. Brooks, Signal Integrity Issues and Printed Circuit Board Design,Prentice Hall PTR, 2003

[2] 顏春煌 編著，802.11無線區域網路理論與實務，旗標出版社，2004 年11 月。

[3] 許永和 編著，USB規格與理論剖析，儒林圖書，2009 年9 月。

[4] Document: 327216-001,” USB 3.0* Radio Frequency Interference Impact on 2.4 GHz Wireless Devices,” Intel Corporation, April 2012

[5] 鍾軒禾，「高頻傳輸導致電磁雜訊高速介面須先解決射頻干擾」，新通訊元件雜誌，2016 年 11 月。