US4290033A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Shallow bulk acoustic wave devices employing energy trapping
Assignee: Northrop Grumman Corp
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Filing: 1979-06-04
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Granted: 1981-09-15
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Expires: 1999-06-04
Abstract
Abstract Energy trapping elements for use with shallow bulk acoustic wave devices of various kinds, to minimize the insertion loses in such devices due to spreading of electroacoustic energy into the crystal substrate upon which the devices are constructed. Electroacoustic energy propagated in a substrate is trapped close to the surface of the substrate by means of trapping elements comprising a plurality of strips or grooves disposed on the surface of the substrate in the path of the propagated energy, and oriented approximately perpendicularly to the direction of propagation. The spacing of the elements is such that their stop-band frequency, at which energy will be reflected, is substantially different from the characteristic center frequency of the entire device, in order that the elements will serve a purely trapping function and not a reflecting function.
Inventors
- 👤 Reynold S. Kagiwada
- 👤 Kuo-Hsiung Yen
- 👤 Kei-Fung Lau
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 07:24
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/02; H03H9/02535; H03H9/02637; H03H9/02685; H03H9/02692; H03H9/027; H03H9/02236; H03H9/02653; H03H9/02716; H03H9/02795
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
79 words
A shallow bulk acoustic wave device, comprising: a piezoelectric substrate having a surface; at least one sending transducer and at least one receiving transducer, both disposed on said substrate surface in such a manner as to provide substantial coupling of shallow bulk acoustic waves and negligible coupling of surface acoustic waves; and means for trapping electroacoustic energy close to said substrate surface, to reduce spreading of the energy into the substrate and thereby reduce insertion loss of the device.
Claim 2
Dependent Claim
79 words
A shallow bulk acoustic wave device, comprising: a piezoelectric substrate having a surface; at least one sending transducer and at least one receiving transducer, both disposed on said substrate surface in such a manner as to provide substantial coupling of shallow bulk acoustic waves and negligible coupling of surface acoustic waves; and means for trapping electroacoustic energy close to said substrate surface, to reduce spreading of the energy into the substrate and thereby reduce insertion loss of the device.
Claim 3
Dependent Claim
41 words
A shallow bulk acoustic wave device as set forth in claim 1, wherein said means for trapping electroacoustic energy include a plurality of strips disposed on said surface in the path of shallow bulk acoustic waves propagated from said sending transducer.
Claim 4
Dependent Claim
57 words
A shallow bulk acoustic wave device as set forth in claim 2, wherein said strips are conductive, parallel, substantially perpendicular to the direction of propagation, and spaced to provide a stop-band frequency range substantially different from the characteristic frequency of operation of said device, whereby said conductive strips have practically no reflective effect on the propagated energy.
Claim 5
Dependent Claim
38 words
A shallow bulk acoustic wave device as set forth in claim 3, wherein said strips are spaced to provide a stop-band frequency range approximately 25 percent higher in frequency than the characteristic frequency of operation of the device.
Claim 6
Dependent Claim
41 words
A shallow bulk acoustic wave device as set forth in claim 1, wherein said means for trapping electroacoustic energy include a plurality of grooves in said surface, positioned in the path of shallow bulk acoustic waves propagated from said sending transducer.
Claim 7
Dependent Claim
31 words
A shallow bulk acoustic wave device as set forth in claim 1, wherein said means for trapping the electroacoustic energy include a dielectric layer disposed on said surface between said transducers.
Claim 8
Dependent Claim
101 words
A shallow bulk acoustic wave delay line, comprising: a piezoelectric substrate having a surface; a sending interdigital transducer disposed on said surface in such a manner as to propagate shallow bulk acoustic waves into said substrate, when energized by an appropriate electrical signal; a receiving interdigital transducer disposed on said surface in a position to receive the shallow bulk acoustic waves and convert them back into an electrical signal; and energy trapping means also disposed on said surface, between said sending and receiving transducers, to trap electroacoustic energy close to said surface and minimize spreading of the energy into said substrate.
Claim 9
Dependent Claim
101 words
A shallow bulk acoustic wave delay line, comprising: a piezoelectric substrate having a surface; a sending interdigital transducer disposed on said surface in such a manner as to propagate shallow bulk acoustic waves into said substrate, when energized by an appropriate electrical signal; a receiving interdigital transducer disposed on said surface in a position to receive the shallow bulk acoustic waves and convert them back into an electrical signal; and energy trapping means also disposed on said surface, between said sending and receiving transducers, to trap electroacoustic energy close to said surface and minimize spreading of the energy into said substrate.
Claim 10
Dependent Claim
31 words
A shallow bulk acoustic wave delay line as set forth in claim 7, wherein said energy trapping means includes a plurality of strips formed on said surface in the propagation path.
Claim 11
Dependent Claim
42 words
A shallow bulk acoustic wave delay line as set forth in claim 8, wherein: said strips are parallel, substantially perpendicular to the propagation path, and spaced to provide a stop-band frequency substantially different from the characteristic response frequency of said delay line.
Claim 12
Dependent Claim
31 words
A shallow bulk acoustic wave delay line as set forth in claim 7, wherein said energy trapping means includes a plurality of grooves formed in said surface in the propagation path.
Claim 13
Dependent Claim
29 words
A shallow bulk acoustic wave delay line as set forth in claim 7, wherein said energy trapping means includes a layer disposed on said surface in the propagation path.
Claim 14
Dependent Claim
20 words
A shallow bulk acoustic wave delay line as set forth in claim 11, wherein said layer is a metal layer.
Claim 15
Dependent Claim
20 words
A shallow bulk acoustic wave delay line as set forth in claim 11, wherein said layer is a dielectric layer.
Claim 16
Dependent Claim
60 words
A shallow bulk acoustic wave delay line as set forth in claim 7, and further including: a multistrip coupler located between said sending and receiving transducers; and second energy trapping means, said first energy trapping means being located between said sending transducer and said coupler, and said second energy trapping means being located between said coupler and said receiving transducer.
Claim 17
Dependent Claim
78 words
A shallow bulk acoustic wave delay line as set forth in claim 7, and further including: at least one additional interdigital receiving transducer spaced along the propagation path on said surface, to provide a tapped output from said delay line; at least one additional energy trapping means disposed on said surface before said additional receiving transducer, to trap energy near said surface and thereby minimize spreading of the energy into the substrate and resultant attenuation in said device.
Claim 18
Dependent Claim
43 words
A shallow bulk acoustic wave delay line as set forth in claims 14 or 15, wherein said energy trapping means each include a plurality of parallel grooves that are formed in said surface and are in and substantially perpendicular to the propagation path.
Claim 19
Dependent Claim
34 words
A shallow bulk acoustic wave delay line as set forth in claims 14 and 15, wherein said energy trapping means each include a plurality of strips formed on said surface in the propagation path.
Claim 20
Dependent Claim
42 words
A shallow bulk acoustic wave delay line as set forth in claim 17, wherein said strips are parallel, substantially perpendicular to the propagation path, and spaced to provide a stop-band frequency substantially different from the characteristic response frequency of said delay line.
Claim 21
Dependent Claim
21 words
A shallow bulk acoustic wave delay line as set forth in claim 18, wherein said strips are formed of conductive material.
Claim 22
Dependent Claim
21 words
A shallow bulk acoustic wave delay line as set forth in claim 18, wherein said strips are formed of dielectric material.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-09-14 | 1985-03-16 | 1985-09-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-09-14 | 1989-03-16 | 1989-09-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-09-14 | 1993-03-16 | 1993-09-15 | $7700.00 | Window Closed / Lapsed |