Patent US3983518A successfully refreshed from Google Patents.
US3983518A
Expired / Lapsed
US
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Filter chain
Assignee: Nederlanden Posterijen Telegrafie en Telefonie Staatsbedrif der
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Filing: 1975-04-24
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Granted: 1976-09-28
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Expires: 1995-04-24
Abstract
Abstract Filter chain comprising a number of monolithic units of piezoelectric material, which units vibrate according to the thickness shear mode and are provided with at least two acoustically coupled resonators and are coupled electrically one to another. The acoustic coupling between said resonators is equal for all units, whereas the electric coupling impedances between the units are substantially ohmic. Due to this the pass band of the filter is determined by the acoustic couplings and there is no need for an adjustment of the electric coupling between the units.
Inventors
- 👤 Jan Adrianus Bezemer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 12:41
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/46; H03H9/54; H03H9/542
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
95 words
A band-pass filter chain for passing frequencies within a given frequency band comprising, a plurality of monolithic filter units made of quartz or other piezoelectric material and adapted to vibrate according to the thickness shear mode, each filter unit being provided with at least two acoustically coupled resonators, said filter units being coupled electrically so that the electric coupling impedances within the frequency pass band of the filter chain are substantially ohmic, the electric coupling impedances being very large with respect to the equivalent acoustic coupling impedances and the acoustic coupling coefficients all being equal.
Claim 2
Dependent Claim
95 words
A band-pass filter chain for passing frequencies within a given frequency band comprising, a plurality of monolithic filter units made of quartz or other piezoelectric material and adapted to vibrate according to the thickness shear mode, each filter unit being provided with at least two acoustically coupled resonators, said filter units being coupled electrically so that the electric coupling impedances within the frequency pass band of the filter chain are substantially ohmic, the electric coupling impedances being very large with respect to the equivalent acoustic coupling impedances and the acoustic coupling coefficients all being equal.
Claim 3
Dependent Claim
45 words
A band-pass filter chain according to claim 1, wherein the filter chain comprises a filter units each having three resonators and b filter units each having two resonators all electrically coupled together whereby 2a + b + 1 resonances fall within the frequency pass band.
Claim 4
Dependent Claim
62 words
A band-pass filter chain according to claim 1 wherein the electric coupling impedance comprises an external inductance which, together with the internal output or input capacitance of a filter unit, forms a parallel resonance circuit having the same resonance frequency as the filter units, the inductance value being chosen to be about 50% higher than the theoretically calculated value to produce resonance.
Claim 5
Dependent Claim
106 words
A band-pass filter circuit comprising a plurality of monolithic filter units adapted to vibrate in response to an applied electric signal and each of which includes at least two acoustically coupled resonators, said filter units all having the same acoustic coupling coefficients, and electric coupling impedance means electrically coupling said plurality of filter units together in cascade so as to provide a substantially ohmic or phase-shift-free electric coupling between units within the frequency pass band of the filter circuit, the electric coupling impedance means being chosen to have an impedance value that is greater than that of the equivalent acoustic coupling impedance of a filter unit.
Claim 6
Dependent Claim
106 words
A band-pass filter circuit comprising a plurality of monolithic filter units adapted to vibrate in response to an applied electric signal and each of which includes at least two acoustically coupled resonators, said filter units all having the same acoustic coupling coefficients, and electric coupling impedance means electrically coupling said plurality of filter units together in cascade so as to provide a substantially ohmic or phase-shift-free electric coupling between units within the frequency pass band of the filter circuit, the electric coupling impedance means being chosen to have an impedance value that is greater than that of the equivalent acoustic coupling impedance of a filter unit.
Claim 7
Dependent Claim
40 words
A band-pass filter circuit as claimed in claim 4 wherein said electric coupling impedance means includes a separate inductor connected in shunt with the output resonator of one filter unit and the input resonator of the next succeeding filter unit.
Claim 8
Dependent Claim
41 words
A band-pass filter circuit as claimed in claim 4 wherein each filter unit includes a body of piezoelectric material adapted to vibrate in the thickness shear mode and said electric coupling impedance means includes a separate inductor between adjacent filter units.
Claim 9
Dependent Claim
67 words
A band-pass filter circuit as claimed in claim 4 wherein said electric coupling impedance means includes a separate inductor which forms a parallel resonant circuit with the internal capacitance of a filter unit and having the same resonant frequency as the filter unit, the inductor being chosen to have an inductance value about 50 per cent higher than the theoretical value required to produce said resonant frequency.
Claim 10
Dependent Claim
58 words
A band-pass filter circuit as claimed in claim 4 wherein the filter circuit comprises A filter units each having three acoustically coupled resonators and B filter units each having two acoustically coupled resonators with all filter units electrically coupled together to produce 2A + B + 1 resonant frequencies within the frequency pass band of the filter circuit.
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) | 1979-09-28 | 1980-03-29 | 1980-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-09-28 | 1984-03-29 | 1984-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-09-28 | 1988-03-29 | 1988-09-28 | $7700.00 | Window Closed / Lapsed |