USB在數位機上盒應用中之訊號完整性及電磁干擾研究

Abstract

本篇論文以數位機上盒(Set Top Box，STB)為實驗平台，研究通用串列匯流排(Universal Serial Bus，USB)差模傳輸在STB應用時的訊號完整性（Signal Integrity，SI）與電磁干擾(Electromagnetic Interference，EMI)。

針對訊號完整性分析，本論文利用HFSS軟體進行模擬，由模擬與實作中可發現，使用正確的印刷電路板(Printed Circuit Board，PCB)設計及減少電容效應可以有效提升訊號完整性及USB眼圖品質。針對電磁干擾分析，本論文進一步探討IC內部週期性訊號透過USB線路所產生的電磁干擾問題。根據實作結果，採用增加Ground Bonding Wire的疏導方式，對於480- 及960-MHz的高階諧波輻射可以分別獲得4- 及16-dB的改善效果。

This thesis employs the Set Top Box (STB) as an experimental platform to study the signal integrity (SI) and the electromagnetic interference (EMI) issues of the Universal Serial Bus (USB) differential transmission in STB application.

For the signal integrity analysis, the thesis uses HFSS to do the simulation. From the simulation result and the circuit implementation, a correct printed circuit board (PCB) design and by reducing capacity effect will significantly increase the quality of the signal integrity and USB eye diagram. For the electromagnetic interference (EMI) analysis, this thesis further discusses the EMI issue which was generated by the periodic signal inside the IC through the USB circuit. Based on the implementation circuit, the result shows 4- and 16-dB improvements in EMI radiated by 480- and 960-MHz higher-order harmonics, respectively, by increasing the dredge of the ground bonding wire.