- 學位論文
差動彎曲線路在時域的分析
Time-Domain Analysis of a Bend of Differential Microstrip Line
摘要
摘要 在科技日新月異的今天，數位電子產品的處理速度已經是越來越快速，一般的”單端傳輸電路”(Single-end transmission line)已經是無法達到高速度的要求了，”差動傳輸電路”(differential-transmission line)的應用也越來越廣範的被電子界所需求。差動電路的”優點”是高速度、可以避免外界的雜訊干擾，”缺點”是差動線路的品質要求很高，2條線路必須是對稱(阻抗需相等)且傳輸速度是相同的才能達到信號不失真而儀器不當機的要求。 為了避免以上的缺點，目前PCB(Print Circuit Board)在處理差動線路時都避免使2傳輸線轉90彎的作法，這樣可以減少線路阻抗的不匹配使信號產生失真，而採用2個45的折角達到90彎曲的目的。在這種情況下另外一個要求是2個45的折角之間的距離不能相距太短。這樣的佈線設計會大大的浪費PCB板面的空間，在速度日益求快且產品體積日益縮小的當兒，事實上直接轉彎90的差動線路是很好的設計，但是直接90的彎因為差動線路的不等長必定使2差動信號產生不同步。 為了要改善這種問題，有人提出UC-PBG(Unplanar Compact Photonic Band-Gap)的蝕刻技術在Ground plane刻上使產生迴路的L與C ，以Slow wave 的技術改善差動線路不等長產生不同步的問題[11][18][19]。另一種是直接在Microstrip line上使用Meander line 來延遲差動線路不等長的問題[20]。 這兩種技術個有其憂缺點，UC-PBG因容易增加成本不容易在工業界實現。而Meander line的技術在轉折角與線與線距離容易產生L與C使阻抗不連續，不是很理想的設計。 本論文的主要目地是提出一方法將在Bend differential line 旁邊產生寄生L,C改善在分析直接90的彎因為差動線路的不等長的TD問題。如何應用一些改善結構的技術補償差動線的不同長度的問題，使90彎曲的差動線路能縮小時間的差異。文中我們使用了FTDT模擬軟體來模擬90彎曲結構的時間差異，然後我們以應用軟體抽出Lump circuit 的L(Self inductance) , C(Self capacitance),Lm(Mutual inductance),Cm(Mutual capacitance) 電路並分析結構的差異。最後以Eye-pattern的統計技術驗證最後的結果差異。
關鍵字
差動彎曲線路並列摘要
Abstract The technique of the electronic industry moving fast, the conventional single-end transmission line can not meet the fast speed enough, and the differential transmission lines are more important to be used in all electronic industry field. The advantages of the differential lines are of fast transmission speed, immunity against electromagnetic interference, but the drawback is necessary to support 2 symmetry characteristic transmission line(same impedance) and equalize propagation delay，the differential signal will not distortion and function down. The 90 bend differential transmission lines will not used in high-seed PCB(Print Circuit Board)circuit, this is because the mismatch impedance and undesired phase delay will cause the distortion problem. So the conventional skill can only to deal with the 90 bend of differential transmission lines with two 45 bends, and the two 45 bends distance can not be too near together to cause the distortion signal. More fast-speed and smaller packages are the trend in the future, so there is not more large space in PCB for two 45 bend microstrip, the 90 bend differential transmission lines is a good chose for small PCB space and high-speed circuit today, but need to improve the un-equalize propagation delay problem. The object of this thesis is to propose a method for compensate an un-desired phase delay caused by unequal-length differential transmission line-s. The propagation delay of a bend of differential transmission lines can be improved by disposing structure to the unequal-length differential transmission lines We use the FTDT simulation software to simulate the bend of differential transmission lines. And the method extracts the L(Self inductance), C(Self capacitance), Lm(Mutual inductance), Cm(Mutual capacitance) to mo-del the coupling circuit, and analyze the circuit difference. Finally we measure the unequal-length differential transmission lines jitter of eye-pattern function of Sampling Scope.