US3878407A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Surface wave electromechanical filter
Assignee: Thales SA
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Filing: 1973-12-18
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Granted: 1975-04-15
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Expires: 1993-12-18
Abstract
Abstract The present invention relates to elastic surface wave electromechanical filters utilising interdigitated transducers. The electromechanical filter in accordance with the invention is made of a piezoelectric substrate carrying on each of its opposite main faces a pair of side-by-side comb type transducers for forming two collateral transmission channels coupled to a balanced-unbalanced electrical transmission device.
Inventors
- 👤 Pierre Hartemann
- 👤 Francel Genauzeau
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 13:26
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/02; H03H9/02535; H03H9/0296; H03H9/02543; H03H9/125; H03H9/145; H03H9/14502; H03H9/14508
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
119 words
A surface wave electromechanical filter having two terminal pairs and comprising: a piezoelectric substrate having two main faces facing one another, first and second interdigitated transducer means arranged on one of said main faces for forming a pair of collateral radiator elements, third and fourth interdigitated transducer means arranged on the other one of said main faces for forming a pair of further collateral radiator elements, at least one curved face linking with one another said main faces, first electrical connecting means for parallel connection of said collateral radiator elements with one of said terminal pairs, and balanced-unbalanced electrical connecting means for connecting the other of said terminal pairs to the respective terminals of said further collateral radiator elements.
Claim 2
Dependent Claim
119 words
A surface wave electromechanical filter having two terminal pairs and comprising: a piezoelectric substrate having two main faces facing one another, first and second interdigitated transducer means arranged on one of said main faces for forming a pair of collateral radiator elements, third and fourth interdigitated transducer means arranged on the other one of said main faces for forming a pair of further collateral radiator elements, at least one curved face linking with one another said main faces, first electrical connecting means for parallel connection of said collateral radiator elements with one of said terminal pairs, and balanced-unbalanced electrical connecting means for connecting the other of said terminal pairs to the respective terminals of said further collateral radiator elements.
Claim 3
Dependent Claim
35 words
A surface wave electromechanical filter as claimed, in claim 1, wherein means for absorbing said surface waves are provided on one of the surface portions of said substrate, linking with one another said main faces.
Claim 4
Dependent Claim
25 words
A surface wave electromechanical filter as claimed in claim 1, wherein said balanced-unbalanced electrical connecting means comprise a transformer having at least one centre-tapped winding.
Claim 5
Dependent Claim
39 words
A surface wave electromechanical filter as claimed in claim 1, wherein said balanced-unbalanced electrical connecting means comprise a differential amplifier having two pairs of terminals; voltages of equal magnitude and opposite sign appearing across said two pairs of terminals.
Claim 6
Dependent Claim
26 words
A surface wave electromechanical filter as claimed in claim 4, wherein the pairs of terminals of said differential amplifier are the input terminals of said amplifier.
Claim 7
Dependent Claim
34 words
A surface wave electromechanical filter as claimed in claim 1, wherein said balanced-unbalanced electrical connecting means comprise an adder circuit having two inputs and a phase inverter circuit connected to one of said inputs.
Claim 8
Dependent Claim
51 words
A surface wave electromechanical filter as claimed in claim 1, wherein said first and second interdigitated transducer means have a common electrode constituted by a comb structure with a double set of teeth, and two further electrodes with single sets of teeth, respectively arranged at each side of said common electrode.
Claim 9
Dependent Claim
21 words
A surface wave electromechanical filter as claimed in claim 1, wherein said interdigitated transducer means have uniformly spaced arrays of teeth.
Claim 10
Dependent Claim
21 words
A surface wave electromechanical filter as claImed in claim 1, wherein said interdigitated transducer means have non-uniformly spaced arrays of teeth.
Claim 11
Dependent Claim
22 words
A surface wave electromechanical filter as claimed in claim 1, wherein said piezoelectric substrate is constituted by a wafer of bismuth germanate.
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) | 1978-04-14 | 1978-10-14 | 1979-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-14 | 1982-10-14 | 1983-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-14 | 1986-10-14 | 1987-04-15 | $7700.00 | Window Closed / Lapsed |