以鼠競環混成器與枝幹耦合器為基礎之寬頻帶通濾波器合成與設計

Abstract

本論文發展以鼠競環混成器與枝幹耦合器為基礎之寬頻帶通濾波器架構，並提出完整的電路解析以及系統化的濾波器合成方法。所提出之兩種以鼠競環混成器為基礎的寬頻帶通濾波器架構分別具有一對可控制虛頻率位置的零點以及一對可控制實頻率位置的零點，藉由選擇適當的虛頻率零點位置可以使濾波器的通帶具有平坦的群延遲響應，而選擇適當的實頻率零點位置，則可以改善濾波器的選擇性。最後，利用雙側平行步階阻抗帶線實現具有帶拒響應以及寬上止帶之微小化寬頻鼠競環帶通濾波器。此外，亦提出兩種以枝幹耦合器為基礎之寬頻帶通濾波器架構，其分別具有一對可控制實頻率位置的零點以及兩對可控制實頻率位置的零點，此類寬頻帶通濾波器具有很高的選擇性，而就我們所知，目前並沒有以枝幹耦合器為基礎的寬頻帶通濾波器被提出。

This dissertation develops the configurations of hybrid ring and branch line coupler based wideband bandpass filters. The full analysis and systematic synthesis method are also presented. Two kinds of hybrid ring based wideband bandpass filters are proposed according to the position of the controllable transmission zero pair. The filter has a controllable transmission zero pair on the imaginary frequency that they can be arranged to improve the group delay flatness. On the other hand, the filter has a controllable transmission zero pair on the real frequency and the desired stopband suppression can be obtained by adjusting the optimal position of them. Finally, the double-sided parallel-strip stepped-impedance line structure is used to implement a miniaturized hybrid ring wideband bandpass filter with a notched band and an improved upper stopband. In addition, two types of branch line coupler based wideband bandpass filters are demonstrated. One has a transmission zero pair, and the other has two transmission zero pairs. They have good selectivity. To the best of our knowledge, the wideband branch line coupler based bandpass filter has not yet been presented before.