DocumentCode :
844797
Title :
Microstrip Parallel-Coupled Filters With Cascade Trisection and Quadruplet Responses
Author :
Lu, Jhe-Ching ; Liao, Ching-Ku ; Chang, Chi-Yang
Author_Institution :
Dept. of Commun. Eng., Nat. Chiao Tung Univ., Hsinchu
Volume :
56
Issue :
9
fYear :
2008
Firstpage :
2101
Lastpage :
2110
Abstract :
Microstrip parallel-coupled filters with generalized Chebyshev responses are presented. The basic structure of the proposed filter is a conventional parallel-coupled filter of which the physical dimensions can be easily obtained by the well-known analytical method. With the aid of the equivalent circuit corresponding to a conventional parallel-coupled filter, the relative insertion phase from source or load to each open end of resonators can be easily obtained by observing the two-port admittance matrix. Applying the cross coupling from source or load to a proper nonadjacent resonator, a trisection or a quadruplet coupling scheme can be realized with prescribed transmission zeros. More importantly, the proposed trisection can be designed to have a transmission zero on the lower or upper stopband by just adjusting the length of the cross-coupling strip. Using the proposed structure, the conventional time-consuming adjusting procedure to obtain initial physical dimensions of filters is no longer required. In this paper, a fourth-order parallel-coupled filter is used as the basic structure to demonstrate various combinations of transmission zeros. Simulated and measured results are well matched.
Keywords :
equivalent circuits; microstrip filters; poles and zeros; resonator filters; cascade trisection; equivalent circuits; generalized Chebyshev responses; microstrip parallel-coupled filters; quadruplet coupling; relative insertion phase; resonator filters; transmission zeros; two-port admittance matrix; Cascade quadruplet (CQ); cascade trisection (CT); cross coupling; mixed cascaded quadruplet and trisection; parallel-coupled filter; transmission zero;
fLanguage :
English
Journal_Title :
Microwave Theory and Techniques, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9480
Type :
jour
DOI :
10.1109/TMTT.2008.2002226
Filename :
4607253
Link To Document :
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