Title:
LONGITUDINAL COUPLING DUAL MODE SAW FILTER
Document Type and Number:
Japanese Patent JP3419949
Kind Code:
B2
Abstract:
PURPOSE: To attain a low broad band loss and to increase an out-band attenuation for a high frequency band by specifying the center interval of innermost electrode fingers of an interdigital transducer(IDT) so as to provide a space and arranging specific grating to the space at an equal interval.
CONSTITUTION: An input IDT 2 is arranged in the vicinity of the center, output IDTs 3, 3 are provided to both sides, and gratings 5, 5 are arranged between the IDTs 2 and 3 on the surface of a piezoelectric substrate 1 along a propagation direction of a surface acoustic wave(SAW) and reflectors 4, 4 are provided to both sides of them. In this case, the center interval of innermost electrode fingers to which each IDT faces is selected to be (2n+1)λ/4 (λ is an electrode finger period of the IDT) to provide a space, in which n-sets of gratings are arranged at an equal interval. Then the SAW stimulated by the IDT2 is confined in a region comprising the IDTs 2, 3, 3 by using the reflectors 4, 4 and a wave motion of primary and ternary modes generated by the acoustic coupling between the IDTs is utilized.
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Inventors:
Yuji Ogawa
Application Number:
JP8330195A
Publication Date:
June 23, 2003
Filing Date:
March 14, 1995
Export Citation:
Assignee:
Toyo Communication Equipment Co., Ltd.
International Classes:
H03H9/145; H03H9/25; H03H9/64; (IPC1-7): H03H9/145; H03H9/25; H03H9/64
Domestic Patent References:
| JP6177703A | ||||
| JP1212015A | ||||
| JP4269010A | ||||
| JP5017951A | ||||
| JP5267990A | ||||
| JP62188512A |