US3596212A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical band-pass filter employing monolithic crystals
Assignee: The General Electric Company PLC
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Filing: 1969-11-06
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Granted: 1971-07-27
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Expires: 1989-11-06
Abstract
Abstract An electrical band-pass filter comprising two quartz slabs each slab having at least two pairs of electrodes each of which pairs sandwiches a portion of the slab to form a mechanical resonator. The resonators are coupled together in a series, adjacent resonators on the same slab being coupled together mechanically, via the material of the slab, and adjacent resonators on different slabs being coupled together electrically, via a capacitor. The construction is effectively a monolithic crystal filter which has been divided into two halves. This reduces mechanical coupling between the input and output of the filter, and thus improves the stop-band performance of the filter. The slabs have different thicknesses and different electrode geometries, thus ensuring that unwanted resonances in the two slabs are at different frequencies. The slabs are mounted backto-back on a conducting screen which electrically shields the slabs from each other. The filter is designed as a whole to have a Chebyshev-type response.
Inventors
- 👤 John Francis Werner
- 👤 Arthur Joseph Dyer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:39
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/46; H03H9/54; H03H9/58
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
182 words
An electrical band-pass filter comprising: at least two single-crystal slabs of piezoelectric crystalline material, each having two major faces; at least two pairs of electrodes on each slab, one electrode of each pair on each said major face, each said pair sandwiching a portion of the slab so as to form a mechanical resonator, and each said pair being separated from other electrodes on that slab by an uncoated portion of the slab, each said slab having a first set of thickness modes of vibration having resonance frequencies within the pass band of the filter and in which modes the vibrations are substantially trapped under said electrodes and a second set of modes of vibration having resonance frequencies outside the pass band of the filter; and input and output terminals between which said resonators are coupled in a series, the coupling between resonators on the same slab being mechanical only, by way of an evanescent mode in a said uncoated portion, and the coupling between resonators on different slabs being by way of electrical coupling means interconnecting the electrodes of those resonators.
Claim 2
Dependent Claim
182 words
An electrical band-pass filter comprising: at least two single-crystal slabs of piezoelectric crystalline material, each having two major faces; at least two pairs of electrodes on each slab, one electrode of each pair on each said major face, each said pair sandwiching a portion of the slab so as to form a mechanical resonator, and each said pair being separated from other electrodes on that slab by an uncoated portion of the slab, each said slab having a first set of thickness modes of vibration having resonance frequencies within the pass band of the filter and in which modes the vibrations are substantially trapped under said electrodes and a second set of modes of vibration having resonance frequencies outside the pass band of the filter; and input and output terminals between which said resonators are coupled in a series, the coupling between resonators on the same slab being mechanical only, by way of an evanescent mode in a said uncoated portion, and the coupling between resonators on different slabs being by way of electrical coupling means interconnecting the electrodes of those resonators.
Claim 3
Dependent Claim
25 words
An electrical band-pass filter according to claim 1, wherein the resonance frequencies of said second set of modes of vibration are different for each slab.
Claim 4
Dependent Claim
17 words
An electrical band-pass filter according to claim 2 wherein the slab thickness varies from slab to slab.
Claim 5
Dependent Claim
19 words
An electrical band-pass filter according to claim 2 wherein the shape of the electrodes varies from slab to slab.
Claim 6
Dependent Claim
24 words
An electrical band-pass filter according to claim 2 wherein both the slab thickness and the shape of the electrodes vary from slab to slab.
Claim 7
Dependent Claim
32 words
An electrical band-pass filter according to claim 1 wherein the two said slabs are mounted parallel to each other and are spaced apart in a direction normal to said plane parallel faces.
Claim 8
Dependent Claim
32 words
An electrical band-pass filter according to claim 6 wherein each of the two slabs is mounted on a support member, and the support members are mounted back-to-back on a common support member.
Claim 9
Dependent Claim
24 words
An electrical band-pass filter according to claim 7 wherein said common support member serves to screen the two said slabs electrically from one another.
Claim 10
Dependent Claim
16 words
An electrical band-pass filter according to claim 1 wherein said electrical coupling means comprises a capacitance.
Claim 11
Dependent Claim
12 words
An electrical band-pass filter according to claim 1, having a Chebyshev-type response.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-07-26 | 1975-01-25 | 1975-07-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-07-26 | 1979-01-25 | 1979-07-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-07-26 | 1983-01-25 | 1983-07-27 | $7700.00 | Window Closed / Lapsed |