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Patent US3573673A successfully refreshed from Google Patents.
US3573673A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acoustic surface wave filters
Assignee: Zenith Electronics LLC
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Filing: 1969-01-08
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Granted: 1971-04-06
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Expires: 1989-01-08
Abstract
Abstract A body of piezoelectric material is capable of propagating acoustic surface waves and a first transducing device is coupled to a surface of the body to develop those waves. Spaced on the same surface from that first device is a second transducing device. The spacing is sufficiently small that crosstalk exists between the devices. To reduce the magnitude of that crosstalk, one or more of several different decoupling arrangements are included. These comprise the connection of diametrically opposite transducer electrodes to a common plane of reference potential, the connection of the mutually closest electrodes of the respective transducers to a plane of common reference potential, the disposition of one or more ground electrodes between the transducers and across the path of wave propagation, the development across the transducers of signals balanced with respect to such a plane, the physical shielding of the space generally above one of the transducers, the inclusion of a conductive shield on the surface opposite the wave-propagating surface and the formation of shielding channels in that surface opposite the wave-propagating surface. In addition, the wave propagation path advantageously is caused to be oriented at an angle relative to the end surfaces of the piezoelectric body in order to minimize reflected wave interference.
Inventors
- 👤 Adrian J De Vries
- 👤 Fleming Dias
- 👤 Thomas J Wojcik
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 04:34
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/0023; H03H9/0028; H03H9/0033; H03H9/0038; H03H9/0042; H03H9/02; H03H9/02535; H03H9/02614; H03H9/02622; H03H9/02637; H03H9/02685; H03H9/02818; H03H9/02842; H03H9/02866; H03H9/02874; H03H9/46; H03H9/64
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
154 words
An acoustic filter comprising: a body of piezoelectric material propagative of acoustic surface waves along a surface thereof; a first surface wave interaction device, including a pair of comb-type electrode arrays interleaved with one another, actively coupled to a portion of said surface and having interaction with said body over a predetermined frequency range; a second surface wave interaction device, likewise including a pair of comb-type electrode arrays interleaved with one another, actively coupled to a portion of said surface spaced from said first device by a distance along said surface and defining with said first device a surface wave propagation path that is sufficiently small to effect passive coupling between said devices over said frequency range; and decoupling means, coupling to a plane of reference potential the one electrode array of each of said devices that is physically closest to the other of said devices, for reducing the magnitude of said passive coupling.
Claim 2
Dependent Claim
154 words
An acoustic filter comprising: a body of piezoelectric material propagative of acoustic surface waves along a surface thereof; a first surface wave interaction device, including a pair of comb-type electrode arrays interleaved with one another, actively coupled to a portion of said surface and having interaction with said body over a predetermined frequency range; a second surface wave interaction device, likewise including a pair of comb-type electrode arrays interleaved with one another, actively coupled to a portion of said surface spaced from said first device by a distance along said surface and defining with said first device a surface wave propagation path that is sufficiently small to effect passive coupling between said devices over said frequency range; and decoupling means, coupling to a plane of reference potential the one electrode array of each of said devices that is physically closest to the other of said devices, for reducing the magnitude of said passive coupling.
Claim 3
Dependent Claim
71 words
A filter as defined in cLaim 1 in which said comb-type electrode arrays of each of said devices extend in opposite directions across said path, and in which said decoupling means couples to said reference plane an electrode array of one of said devices that extends in one direction across said path and an electrode array of the other of said devices that extends in the opposite direction across said path.
Claim 4
Dependent Claim
29 words
A filter as defined in claim 1 in which said decoupling means comprises an electrode that is disposed to define an acute angle with the direction of said path.
Claim 5
Dependent Claim
41 words
A filter as defined in claim 1 in which said decoupling means includes means for effecting development of the signal across at least one of said pairs of electrode arrays in balanced relationship with respect to said plane of reference potential.
Claim 6
Dependent Claim
147 words
An acoustic filter comprising: a body of piezoelectric material propagative of acoustic surface waves along a surface thereof; a first surface wave interaction device, including a pair of comb-type electrode arrays interleaved with one another, actively coupled to a portion of said surface and having interaction with said body over a predetermined frequency range; a second surface wave interaction device, likewise including a pair of comb-type electrode arrays interleaved with one another, actively coupled to a portion of said surface spaced from said first device by a distance along said surface and defining with said first device a surface wave propagation path that is sufficiently small to effect passive coupling between said devices over said frequency range; and decoupling means for reducing the magnitude of said passive coupling comprising at least one channel, oriented laterally of said path, in a surface of said body opposite said devices.
Claim 7
Dependent Claim
147 words
An acoustic filter comprising: a body of piezoelectric material propagative of acoustic surface waves along a surface thereof; a first surface wave interaction device, including a pair of comb-type electrode arrays interleaved with one another, actively coupled to a portion of said surface and having interaction with said body over a predetermined frequency range; a second surface wave interaction device, likewise including a pair of comb-type electrode arrays interleaved with one another, actively coupled to a portion of said surface spaced from said first device by a distance along said surface and defining with said first device a surface wave propagation path that is sufficiently small to effect passive coupling between said devices over said frequency range; and decoupling means for reducing the magnitude of said passive coupling comprising at least one channel, oriented laterally of said path, in a surface of said body opposite said devices.
Claim 8
Dependent Claim
31 words
A filter as defined in claim 5 in which an electrically conductive shield is disposed in at least a portion of said channel and coupled to a plane of reference potential.
Claim 9
Dependent Claim
143 words
An acoustic filter comprising: a body of piezoelectric material propagative of acoustic surface waves along a surface thereof; a first surface wave interaction device, including a pair of comb-type electrode arrays interleaved with one another, actively coupled to a portion of said surface and having interaction with said body over a predetermined frequency range; a second surface wave interaction device, likewise including a pair of comb-type electrode arrays interleaved with one another, actively coupled to a portion of said surface spaced from said first device by a distance along said surface and defining with said first device a surface wave propagation path that is sufficiently small to effect passive coupling between said devices over said frequency range; and said devices being so oriented that said propagation path forms an acute angle to at least one end surface of said body of piezoelectric material.
Claim 10
Dependent Claim
143 words
An acoustic filter comprising: a body of piezoelectric material propagative of acoustic surface waves along a surface thereof; a first surface wave interaction device, including a pair of comb-type electrode arrays interleaved with one another, actively coupled to a portion of said surface and having interaction with said body over a predetermined frequency range; a second surface wave interaction device, likewise including a pair of comb-type electrode arrays interleaved with one another, actively coupled to a portion of said surface spaced from said first device by a distance along said surface and defining with said first device a surface wave propagation path that is sufficiently small to effect passive coupling between said devices over said frequency range; and said devices being so oriented that said propagation path forms an acute angle to at least one end surface of said body of piezoelectric 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) | 1974-04-05 | 1974-10-05 | 1975-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-05 | 1978-10-05 | 1979-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-05 | 1982-10-05 | 1983-04-06 | $7700.00 | Window Closed / Lapsed |