US4814658A
Expired / Lapsed
US
⏱️ 0.0 years remaining
SAW device with continuous finger pattern
Assignee: Nortel Networks Ltd
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Filing: 1987-11-10
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Granted: 1989-03-21
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Expires: 2007-11-10
Abstract
Abstract A SAW device includes aligned IDTs (inter-digital transducers) with a continuous pattern of fingers between their front edges. Each IDT may be symmetrical about its center, and includes front and back edge reflection suppressing regions of fingers of successively decreasing length, which serve to suppress surface acoustic wave reflections at the respective edges. Optional shield regions between the two front edge suppressing regions, and between the back edge suppressing regions and acoustic absorbers, include fingers of successively increasing length complementary to and adjacent the fingers of successively decreasing length of the reflection suppressing regions. The IDTs may be apodized or unapodized, and each IDT may include dummy fingers between its active region and each reflection suppressing region.
Inventors
- 👤 Mark S. Suthers
- 👤 Grantley O. Este
- 👤 Richard W. Streater
- 👤 Blair K. MacLaurin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 05:07
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/02; H03H9/125; H03H9/145; H03H9/14517; H03H9/1452; H03H9/02535; H03H9/02818; H03H9/02842; H03H9/46; H03H9/64; H03H9/6423; H03H9/6433; H03H9/6436
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
96 words
A SAW (surface acoustic wave) device comprising a substrate having two IDTs (inter-digital transducers) thereon aligned for propagation of a surface acoustic wave with a predetermined wavelength lambda between front edges of the IDTs, and a continuous pattern of fingers spaced with a pitch of lambda/4 between the front edges of the IDTs, each of the IDTs including a reflection suppressing region at its front edge, each reflection suppressing region comprising a plurality of spaced electrically interconnected fingers of successively decreasing length, the reflection suppressing regions forming at least part of said continuous pattern of fingers.
Claim 2
Dependent Claim
96 words
A SAW (surface acoustic wave) device comprising a substrate having two IDTs (inter-digital transducers) thereon aligned for propagation of a surface acoustic wave with a predetermined wavelength lambda between front edges of the IDTs, and a continuous pattern of fingers spaced with a pitch of lambda/4 between the front edges of the IDTs, each of the IDTs including a reflection suppressing region at its front edge, each reflection suppressing region comprising a plurality of spaced electrically interconnected fingers of successively decreasing length, the reflection suppressing regions forming at least part of said continuous pattern of fingers.
Claim 3
Dependent Claim
46 words
A SAW device as claimed in claim 1 wherein the continuous pattern of fingers includes a shield region between the reflection suppressing regions at the front edges of the IDTs, the shield region comprising a plurality of electrically interconnected fingers for connection to a ground point.
Claim 4
Dependent Claim
40 words
A SAW device as claimed in claim 2 wherein the shield region includes fingers of successively increasing length complementary to and adjacent the fingers of successively decreasing length of the reflection suppressing region at the front edge of each IDT.
Claim 5
Dependent Claim
33 words
A SAW device as claimed in claim 1 wherein the fingers of the reflection suppressing regions are complementary to and adjacent one another, thereby forming an inclined junction between the reflection suppressing regions.
Claim 6
Dependent Claim
62 words
A SAW device as claimed in claim 4 wherein each IDT includes an active region and a plurality of dummy fingers between the active region and the reflection suppressing region at the front edge of the IDT, the dummy fingers being electrically connected to and being spaced with the same pitch as the fingers of the reflection suppressing region of the IDT.
Claim 7
Dependent Claim
35 words
A SAW device as claimed in claim 1 wherein each IDT includes a reflection suppressing region, comprising a plurality of spaced electrically interconnected fingers of successively decreasing length, at a back edge of the IDT.
Claim 8
Dependent Claim
19 words
A SAW device as claimed in claim 6 wherein each reflection suppressing region comprises at least about 40 fingers.
Claim 9
Dependent Claim
110 words
A SAW device as claimed in claim 3 wherein each IDT includes a reflection suppressing region, comprising a plurality of spaced electrically interconnected fingers of successively decreasing length, at a back edge of the IDT, the SAW device further comprising two further shield regions, each comprising a plurality of electrically interconnected fingers for connection to a ground point, each adjacent to the reflection suppressing region at the back edge of a respective one of the IDTs, each further shield region including fingers of successively increasing length complementary to and adjacent the fingers of successively decreasing length of the respective reflection suppressing region at the back edge of the respective IDT.
Claim 10
Dependent Claim
155 words
A SAW (surface acoustic wave) device comprising a substrate having an IDT (inter-digital transducer) on a surface thereof, the IDT comprising: an active region of inter-digital fingers, for transducing a surface acoustic wave with a predetermined wavelength for propagation on said surface via a front edge of the IDT; a front edge reflection suppressing region, comprising a plurality of spaced electrically interconnected fingers of successively decreasing length, at the front edge of the IDT; a back edge reflection suppressing region, comprising a plurality of spaced electrically interconnected fingers of successively decreasing length, at a back edge of the IDT opposite the front edge; and a plurality of dummy fingers between the active region and each reflection suppressing region; the fingers in the reflection suppressing regions and the dummy fingers all being electrically interconnected and spaced, in the direction of propagation of the surface acoustic wave, with a pitch of one quarter of said predetermined wavelength.
Claim 11
Dependent Claim
155 words
A SAW (surface acoustic wave) device comprising a substrate having an IDT (inter-digital transducer) on a surface thereof, the IDT comprising: an active region of inter-digital fingers, for transducing a surface acoustic wave with a predetermined wavelength for propagation on said surface via a front edge of the IDT; a front edge reflection suppressing region, comprising a plurality of spaced electrically interconnected fingers of successively decreasing length, at the front edge of the IDT; a back edge reflection suppressing region, comprising a plurality of spaced electrically interconnected fingers of successively decreasing length, at a back edge of the IDT opposite the front edge; and a plurality of dummy fingers between the active region and each reflection suppressing region; the fingers in the reflection suppressing regions and the dummy fingers all being electrically interconnected and spaced, in the direction of propagation of the surface acoustic wave, with a pitch of one quarter of said predetermined wavelength.
Claim 12
Dependent Claim
19 words
A SAW device as claimed in claim 9 wherein each reflection suppressing region comprises at least about 40 fingers.
Claim 13
Dependent Claim
15 words
A SAW device as claimed in claim 10 wherein the IDT is an apodized IDT.
Claim 14
Dependent Claim
98 words
A SAW (surface acoustic wave) device comprising a substrate having two IDTs (inter-digital transducers) thereon aligned for propagation of a surface acoustic wave having a predetermined wavelength lambda between front edges of the IDTs, the SAW device further comprising a continuous pattern of fingers spaced with a pitch of lambda/4 between the front edges of the IDTs, at least one inclined junction between two different regions of the SAW device being formed by fingers of successively increasing length complementary to and adjacent fingers of successively decreasing length extending from respective conductive rails at opposite sides of the IDTs.
Claim 15
Dependent Claim
98 words
A SAW (surface acoustic wave) device comprising a substrate having two IDTs (inter-digital transducers) thereon aligned for propagation of a surface acoustic wave having a predetermined wavelength lambda between front edges of the IDTs, the SAW device further comprising a continuous pattern of fingers spaced with a pitch of lambda/4 between the front edges of the IDTs, at least one inclined junction between two different regions of the SAW device being formed by fingers of successively increasing length complementary to and adjacent fingers of successively decreasing length extending from respective conductive rails at opposite sides of the IDTs.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-03-20 | 1992-09-19 | 1993-03-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-03-20 | 1996-09-19 | 1997-03-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-03-20 | 2000-09-19 | 2001-03-21 | $7700.00 | Window Closed / Lapsed |