Design of a dual-band bandpass filter with a wide rejection band

Abstract

本論文提出兩種利用不同抑制方法,完成三個具有抑制倍頻響應之雙頻帶通濾波器。第一個三階雙頻濾波器乃利用步階阻抗共振器所完成的,透過巧妙安排兩個步階阻抗共振器之基頻和倍頻的關係,則可以不需再外加其它元件就可有效達成雙頻帶且具有寬的截止帶;而第二個雙頻濾波器則是引入具有殘段之指叉型電容以及四分之ㄧ波長開路殘段來產生零點,並將這些零點放置於倍頻產生之處以期能夠抑制倍頻並達到寬截止帶;最後一個雙頻濾波器亦是利用四分之ㄧ波長開路殘段所產生的零點來達成寬截止帶。本論文所提出之三個濾波器各有優劣,可視應用之範圍與規格來挑選較符合之濾波器,另外,吾人亦透過實驗數據來驗證濾波器設計理論分析之可行性。We use two methods to suppress the spurious frequency of three dual band bandpass filters in this thesis. The first 3rd dual band filter was composed of stepped impedance resonators. We can achieve dual band and a wide rejection band effectively by arranging the relationship between the base frequency and the spurious frequency skillfully. For the second filter, we introduce interdigital capacitance with stubs and open stubs to produce zeros, and try to locate these zeros in the location of the spurious frequency, therefore we also can achieve a wide rejection band. We also use open stubs to produce zeros and achieve a wide rejection band in the last filter design. The three filters have their pros and cons respectively. Users can choose the best one according to the range and specification of applications. Also, the experimental results show that our filter design is feasible.誌謝 ii文摘要 ivbstract v目錄 vii目錄 ix1章 緒論 1.1 研究動機與問題描述 1.2 文獻回顧 2.3 章節概述 32章 濾波器理論分析 5.1 簡介 5.2 集總式濾波器理論分析 6.3 分散式帶通濾波器理論分析 123章 步階阻抗共振器構成之雙頻帶濾波器 32.1 簡介 32.2 半波長步階阻抗共振器之分析 32.3 具寬截止帶之雙頻帶通濾波器設計 36.4 小結 394章 引入λ/4開路殘段達成寬截止帶之雙頻帶通濾波器 44.1 簡介 44.2 具寬截止帶之雙頻帶通濾波器_1 44.3 具寬截止帶之雙頻帶通濾波器_2 52.4 小結 625章 結論 64考文獻 6

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