具傳輸零點之共面波導摺疊式四分之一波長諧振腔濾波器

Abstract

本計劃擬研究摺疊式共面波導諧振腔及其所構成之各類濾波器如：梳形結構(combline structure)、指叉結構(interdigital structure)、平行耦合結構等。摺疊式之諧振 腔可以縮短其長度，進而縮小整體濾波器之面積。同時，在計劃中我們也將研究此種 摺疊式共面波導諧振腔構成的濾波器之佈局使其能夠產生有限頻率之傳輸零點。初步 之規劃為使用串接四角互耦(cascade quadruplet, CQ)與串接三角互耦(cascade trisection, CT)結構，因為此二結構最為適合前面所述之濾波器結構。佈局上為了避 免中間諧振腔之地導體過遠問題，計劃使用每個諧振腔都有地導體之結構，如此則形 成一種新的耦合結構此也有待深入分析。

In this program, a folded CPW (coplanar waveguide) resonator is proposed. This type of resonator can be used to construct various filters such as combline structure, interdigital structure, parallel coupled structure, etc. The folded resonator is shorter than conventional resonator and the size of whole filter can also be shrunken. In the mean time the layout of the filter will also be studied so that the filter may have finite frequency transmission zeros. Preliminary study shows that the cascade quadruplet (CQ) and cascade trisection (CT) structure is very possible to implement finite frequency transmission zeros. The distance between ground plane and internal resonator of CPW combline or interdigital filter is usually too large and often causes layout problems. We propose a method that inserts ground planes between every two resonators. This newly inserted ground plane changes the coupling and needs to study further.