US3956647A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acoustic surface-wave devices using mono crystalline bismuth silicon oxide substrate
Assignee: US Philips Corp
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Filing: 1974-10-15
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Granted: 1976-05-11
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Expires: 1994-10-15
Abstract
Abstract An acoustic surface wave filter comprising a monocrystalline wafer of bismuth silicon oxide having a special orientation of the ASW propagation surface and the interdigital transducers relative to the crystal plane whereby pick-up of undesired bulk waves is reduced.
Inventors
- 👤 Richard Frank Mitchell
- 👤 Eileen Read
- 👤 Richard Stevens
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 22:03
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/30; H03H9/02; H03H9/02535; H03H9/02543; H03H9/02614; H03H9/02622; H03H9/02818; H03H9/02866
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
176 words
An acoustic surface-wave device comprising a wafer of monocrystalline bismuth silicon oxide having first and second major surfaces and formed so that the first major surface of said wafer which constitutes the acoustic surface-wave propagation surface of the device lies substantially parallel to the crystallographic (111) plane or a crystallographically-equivalent plane, as herein defined, a launching and a receiving interdigital transducer coupled to said first major surface respectively to launch and to receive acoustic surface waves in any one of the directions [1 0 1], [1 1 0] and [0 1 1] or equivalent directions as herein defined in said (111) plane or in any one of the crystallographically-equivalent directions, as herein defined, in said equivalent plane, and means for attenuating bulk waves directed at the second major surface of the wafer, said transducers being spaced apart a distance such that bulk shear waves having a particle motion inclined to said first major surface and launched by one of said transducers in the direction of the other transducer are substantially prevented from reaching said other transducer.
Claim 2
Dependent Claim
176 words
An acoustic surface-wave device comprising a wafer of monocrystalline bismuth silicon oxide having first and second major surfaces and formed so that the first major surface of said wafer which constitutes the acoustic surface-wave propagation surface of the device lies substantially parallel to the crystallographic (111) plane or a crystallographically-equivalent plane, as herein defined, a launching and a receiving interdigital transducer coupled to said first major surface respectively to launch and to receive acoustic surface waves in any one of the directions [1 0 1], [1 1 0] and [0 1 1] or equivalent directions as herein defined in said (111) plane or in any one of the crystallographically-equivalent directions, as herein defined, in said equivalent plane, and means for attenuating bulk waves directed at the second major surface of the wafer, said transducers being spaced apart a distance such that bulk shear waves having a particle motion inclined to said first major surface and launched by one of said transducers in the direction of the other transducer are substantially prevented from reaching said other transducer.
Claim 3
Dependent Claim
38 words
An acoustic surface wave device as claimed in claim 1 wherein the spacing, width and overlap of adjacent electrode elements of at least one of said transducers are chosen so that the device provides a band-pass filter response.
Claim 4
Dependent Claim
62 words
An acoustic surface wave device as claimed in claim 1 wherein the form, spacing and weighting of the electrodes of one interdigital electrode array of one of said transducers are chosen and the space between the launching and receiving transducers is chosen so that the device provides a frequency filter characteristic of the general form shown in FIG. 2 of the drawing.
Claim 5
Dependent Claim
37 words
An acoustic surface wave device as claimed in claim 1 wherein the ends of the wafer transverse to the direction of propagation of the acoustic surface wave make an angle of approximately 70° to said propagation direction.
Claim 6
Dependent Claim
49 words
An acoustic surface wave device as claimed in claim 1 wherein said attenuating means comprises a plurality of discrete recesses formed in the second major surface of the wafer and which extend into the wafer to within at most three acoustic surface wave wavelengths of the first major surface.
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) | 1979-05-11 | 1979-11-10 | 1980-05-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-05-11 | 1983-11-10 | 1984-05-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-05-11 | 1987-11-10 | 1988-05-11 | $7700.00 | Window Closed / Lapsed |