Design of Common-mode Filter by Multi-layer Low Temperature Co-fired Ceramic

• Main Authors: Pei-Ming Chiu, 邱培銘
• Other Authors: Lin-Kun Wu
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/42829955191587082569

碩士 === 國立交通大學 === 電信工程系所 === 93 === 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.