本論文主要研究如何利用短路耦合傳輸線、並聯諧振腔與輸入輸出間的回授電容效應來設計擁有高衰減速度與止帶抑制之二階三零點濾波器。文章內容有包含如何利用短路耦合線架構產生單一傳輸零點、回授電路對傳輸零點的影響與利用並聯諧振器與耦合線架構設計獨立雙零點濾波器，最後設計與利用低溫陶瓷共燒技術在不需打孔且僅需五層金屬層下實作三零點濾波器。實作結果於中心頻率5.15~5.35GHz插入損耗僅2.0dB，低頻於通帶外500MHz即可達-30dB，高頻於900M也可達-30dB的抑制效果，且抑制能力也可維持在30dB左右不錯的特性，濾波器尺寸也只有2.5mm x 2.0mm x 1.0mm，研究結果顯示在此新電路架構下利用低溫陶瓷共燒技術，一個小尺寸、低損耗、三零點的濾波器是可以被實踐的。

The main research of this study is to employ the shorted coupled transmission line, parallel resonators, and feedback capacitors to design a second order bnadpass filter with three transmission zeros and sharp cutoff characteristics. The main studies include how to use coupled transmission line to design a bandpass filter with one transmission zero, the influence of the feedback circuit on transmission zeros, and design the bandpass filter with two independent transmission zeros by changing the coupled-line structure and the parallel LC resonators. The proposed filter with three transmission zeros has been implemented using just five layer of metal without punched holes. The measured insertion loss is less than 2dB between 5.15GHz and 5.35GHz. The rejection is more than 30dB from 3.4GHZ to 4.6GHz and beyond 6.2GHz. The size of this filter is only 2.5mm X 2.0mm X 1.0mm.This study shows, a compact, low loss and high out of band rejection filter, with three transmission zeros by using LTCC technology, is practicable.

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