Patent US4189061A successfully refreshed from Google Patents.
EP0401737A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Saw filter and mobile telephone using same
Assignee: Hitachi Ltd
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Filing: 1990-06-05
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Granted: —
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Expires: 2010-06-05
Abstract
Abstract A plurality of interdigital transducers (IDTs) (2.1-2.7; 4.1-4-6) of a surface acoustic wave bandpass filter (1), each of which has a plurality of electrode fingers arranged in a direction perpendicular to a propagating direction of surface acoustic wave, are connected alternatively to an input terminal (3) and an output terminal (5) of said filter. The IDTs are different in number of electrode fingers and in average value of inter-finger distance from each other and distance between adjacent IDTs are different. At least one of the outermost IDTs has a minimum number of electrode fingers and a maximum average value of inter-finger distance, compared with those of other IDTs.
Inventors
- 👤 Hideo Ohnuki
- 👤 Norio Room 202 Nishikawa-Sou Hosaka
- 👤 Hitoshi C/O Mitakeryou 1545 Watanabe
- 👤 Yun Yamada
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 16:24
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/46; H03H9/64; H03H9/6423; H03H9/6426
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
78 words
A surface acoustic wave bandpass filter comprising a plurality of IDTs arranged in a propagating direction of surface acoustic wave and connected alternatively to an input terminal and an output terminal of said filter, each said IDT having a plurality of electrode fingers extending perpendicularly to the propagating direction of surface acoustic wave, said IDTs being different in number of said electrode fingers and in average value of inter-finger distance from each other and having different inter-transducer distances.
Claim 2
Dependent Claim
78 words
A surface acoustic wave bandpass filter comprising a plurality of IDTs arranged in a propagating direction of surface acoustic wave and connected alternatively to an input terminal and an output terminal of said filter, each said IDT having a plurality of electrode fingers extending perpendicularly to the propagating direction of surface acoustic wave, said IDTs being different in number of said electrode fingers and in average value of inter-finger distance from each other and having different inter-transducer distances.
Claim 3
Dependent Claim
39 words
The surface acoustic wave bandpass filter claimed in claim 1, wherein one of the outermost IDTs has a minimum number of electrode fingers and a maximum average value of inter-electrode finger distance, with respect to those of other IDTs.
Claim 4
Dependent Claim
96 words
A surface acoustic wave bandpass filter comprising a couple of surface acoustic wave devices connected electrically in series, each said surface acoustic wave device including a plurality of IDTs arranged in a propagating direction of surface acoustic wave and connected alternatively to an input terminal and an output terminal of said filter, each said IDT having a plurality of electrode fingers extending perpendicularly to the propagating direction of surface acoustic wave, said IDTs being different in number of said electrode fingers and in average value of inter-finger distance from each other and having different inter-transducer distances.
Claim 5
Dependent Claim
96 words
A surface acoustic wave bandpass filter comprising a couple of surface acoustic wave devices connected electrically in series, each said surface acoustic wave device including a plurality of IDTs arranged in a propagating direction of surface acoustic wave and connected alternatively to an input terminal and an output terminal of said filter, each said IDT having a plurality of electrode fingers extending perpendicularly to the propagating direction of surface acoustic wave, said IDTs being different in number of said electrode fingers and in average value of inter-finger distance from each other and having different inter-transducer distances.
Claim 6
Dependent Claim
40 words
The surface acoustic wave bandpass filter claimed in claim 3, wherein at least one of said outermost IDTs has a minimum number of electrode fingers and a maximum average value of inter-finger distance, with respect to those of other IDTs.
Claim 7
Dependent Claim
61 words
A portable telephone device comprising an antenna, a separator having a terminal connected to said antenna and two terminals, a pair of surface acoustic wave bandpass filters connected to said two terminals of said separator, respectively, each said surface acoustic wave filter claimed in any of claims 1 to 3 and having center frequency different from that of the other filter.
References Cited (Backward Citations)
No citation records indexed.
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