A new design concept for low-loss SAW filters based on different-width split-finger SPUDT

Author

Nakamura, Hiroyuki ; Yamada, Toru ; Ishizaki, Toshio ; Nishimura, Kazunori

Author_Institution

Matsushita Electr. Ind. Co. Ltd., Osaka, Japan

Volume

49

Issue

4

fYear

2001

fDate

4/1/2001 12:00:00 AM

Firstpage

761

Lastpage

768

Abstract

A new design concept of a single-phase unidirectional transducer (SPUDT) has been investigated in this paper. The concept has been realized by using a newly developed different-width split-finger-SPUDT structure, in which the adjacent electrode fingers are given different widths. A symmetrical radiation conductance is obtained by adjusting the electrode finger positions. Computer simulations have confirmed that the electrical 1/Q factor and the directivity have a tradeoff relationship with regard to the finger-width ratio, depending on the metallization thickness used. From the simulation results, the optimum finger-width ratio for achieving a low insertion loss has been obtained. An experimental filter was constructed, which shows good performance, with the insertion loss improved by 1 dB when compared to a conventional electrode-width-controlled-SPUDT filter on an ST-cut quartz substrate

Keywords

code division multiple access; electrodes; mobile radio; surface acoustic wave filters; surface acoustic wave transducers; adjacent electrode fingers; different-width split-finger SPUDT; directivity; electrical 1/Q factor; electrode finger positions; insertion loss; low-loss SAW filters; metallization thickness; single-phase unidirectional transducer; symmetrical radiation conductance; Computational modeling; Computer simulation; Electrodes; Fingers; Insertion loss; Metallization; Performance loss; Q factor; SAW filters; Transducers;

fLanguage

English

Journal_Title

Microwave Theory and Techniques, IEEE Transactions on

Publisher

ieee

ISSN

0018-9480

Type

jour

DOI

10.1109/22.915461

Filename

915461