多層低溫共燒陶瓷共模濾波器之設計

Abstract

本論文針對USB 2.0 高速480Mb/s的傳輸速率設計一個建構在多層LTCC基材內的共模濾波器，元件整體的構造是依循螺旋電感的繞線方式，利用堆疊的方式使正端和負端訊號線交替地配置在不同的層中進而形成一多層結構，然後配合USB的差模阻抗90Ω，設計出一個共模訊號的衰減量大、差模訊號的插入損耗和反射損耗小的共模濾波器。接著再縮小元件的厚度使整體更趨於小型化，但阻抗的不匹配程度隨著正負端訊號線間的距離變小而變大，因此利用平移負端訊號線及調整線寬的方式來增進阻抗的匹配。之後再將無遮蔽雙絞線結構以多層板的方式實現，設計出一雙絞線式的多層共模濾波器，增加元件抵抗雜訊的能力和減少自身輻射及模態轉換所產生的干擾現象，最後利用等效電路來詮釋這三種不同結構的特性表現，分析改變結構對電路參數所帶來的影響。

In this thesis, the purpose is to develop a common-mode filter constructed in multilayer LTCC substance for USB 2.0 high-speed 480Mb/s. This pattern is composed of multilayer structures by stacking positive and negative coils, each in the form of spiral inductor, on alternate layers. The common-mode filter is designed to achieve sufficient common-mode suppression while introducing minimal pass-band insertion loss and mode conversion to the desired differential-mode signal, and match 90Ω differential impedance of USB. In order to miniaturize the size of component, a thinner substrate is needed. But the closer positive and negative coils are, the more differential impedance mismatches. Impedance matching can be improved by offsetting the negative coil and adjusting the width of signal line. In addition, an effect to enhance immunity against noises and reduce the radiated emission and mode conversion of the filter by twisting positive and negative pair is described. Finally, an equivalent circuit model is described and circuit parameters extracted illustrate the effects of routing topologies and structural parameters on filter’s performance.