Patent US3746228A successfully refreshed from Google Patents.
Patent US3904996A successfully refreshed from Google Patents.
US3904996A
Expired / Lapsed
US
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Capacitive weighted acoustic surface wave filter
Assignee: Texas Instruments Inc
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Filing: 1973-12-28
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Granted: 1975-09-09
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Expires: 1993-12-28
Abstract
Abstract A new technique for weighting acoustic surface wave filter interdigital transducers in which transducer pads are first deposited on a substrate, a dielectric layer deposited thereover and interdigital fingers deposited atop the dielectric layer with the fingers having a variable and selectable area where they overlap the dielectric to thereby effectively vary the amount of capacitive coupling of each finger and resulting in an acoustic wave which is uniform across its beam width.
Inventors
- 👤 Ronald C Rosenfeld
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:34
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/02; H03H9/125; H03H9/145; H03H9/14517; H03H9/14523; H03H3/00; H03H3/007; H03H3/08
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
184 words
An acoustic surface wave filter including at least one weighted transducer comprising: substrate means including at least one surface of piezoelectric material, an interdigital acoustic surface wave transducer disposed on said at least one surface of piezoelectric material, said transducer including first and second transducer pads disposed on said piezoelectric surface in aligned spaced apart relationship, a first plurality of fingers disposed on said piezoelectric surface and operably associated with said first transducer pad, a second plurality of fingers disposed on said piezoelectric surface and operably associated with said second transducer pad, said second plurality of fingers being parallel to and interdigitated with said first plurality of fingers so as to have overlapping finger portions, means defining respective capacitive relationships coupling the individual fingers included in said first plurality of fingers to said first transducer pad, means defining respective capacitive relationships coupling the individual fingers included in said second plurality of fingers to said second transducer pad, and said capacitive relationship-defining means being selected to provide a predetermined weighting to the interdigitated first and second pluralities of fingers for obtaining a desired impulse response.
Claim 2
Dependent Claim
184 words
An acoustic surface wave filter including at least one weighted transducer comprising: substrate means including at least one surface of piezoelectric material, an interdigital acoustic surface wave transducer disposed on said at least one surface of piezoelectric material, said transducer including first and second transducer pads disposed on said piezoelectric surface in aligned spaced apart relationship, a first plurality of fingers disposed on said piezoelectric surface and operably associated with said first transducer pad, a second plurality of fingers disposed on said piezoelectric surface and operably associated with said second transducer pad, said second plurality of fingers being parallel to and interdigitated with said first plurality of fingers so as to have overlapping finger portions, means defining respective capacitive relationships coupling the individual fingers included in said first plurality of fingers to said first transducer pad, means defining respective capacitive relationships coupling the individual fingers included in said second plurality of fingers to said second transducer pad, and said capacitive relationship-defining means being selected to provide a predetermined weighting to the interdigitated first and second pluralities of fingers for obtaining a desired impulse response.
Claim 3
Dependent Claim
28 words
An acoustic surface wave filter as set forth in claim 1, wherein said overlapping finger portions of said first and second pluralities of fingers are of equal lengths.
Claim 4
Dependent Claim
57 words
An acoustic surface wave filter as set forth in claim 2, wherein said first and second transducer pads contain indentations into which corresponding fingers extend with the fingers being spaced from the indentation-defining transducer pad portions such that the opposing edges of the fingers and the indentation-defining transducer pad portions form capacitors comprising said capacitive relationship-defining means.
Claim 5
Dependent Claim
90 words
An acoustic surface wave filter as set forth in claim 2, wherein said capacitive relationship-defining means comprises respective layers of dielectric material disposed over each of said first and second transducer pads, a portion of each finger in said first and second pluralities of fingers overlying a portion of the dielectric layer associated with its respective transducer pad to form capacitors, and the size of the portion of each finger overlying the respective dielectric layer being determinative oF the capacitive coupling of that finger to the transducer pad corresponding thereto.
Claim 6
Dependent Claim
34 words
An acoustic surface wave filter as set forth in claim 4, wherein the sizes of the portions of said fingers overlying the respective said dielectric layer are varied to obtain a desired impulse response.
Claim 7
Dependent Claim
64 words
An acoustic surface wave filter as set forth in claim 5, further including a second interdigital acoustic surface wave transducer disposed on said at least one piezoelectric surface of said substrate means, said second transducer also being weighted in the manner of the first transducer, and the total predetermined weighting for the acoustic surface wave filter being divided between said first and second transducers.
References Cited (Backward Citations)
US3582540A
Cited
US3688223A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-08 | 1979-03-10 | 1979-09-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-08 | 1983-03-10 | 1983-09-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-08 | 1987-03-10 | 1987-09-09 | $7700.00 | Window Closed / Lapsed |