Patent US3993959A successfully refreshed from Google Patents.
US3993959A
Expired / Lapsed
US
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Second-order canonical active filter
Assignee: Nortel Networks Ltd
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Filing: 1974-12-13
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Granted: 1976-11-23
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Expires: 1994-12-13
Abstract
Abstract A high-pass notch filter with variable gain that may be greater than unity is realized using a differential amplifier and only two capacitors that can be equal. The transmission zero and pole frequency are completely independent of the amplifier d-c gain. Three embodiments of the filter are illustrated, thus extending the available range of the gain to cover all requirements.
Inventors
- 👤 Stalin A. Boctor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 11:42
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/126
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
141 words
A second-order canonical active filter comprising: input, output and common terminals; a differential amplifier having inverting and noninverting inputs, and an output, the output of the differential amplifier being connected to said output terminal; a first set of impedances including first and second impedance arms connected between said inverting and noninverting inputs respectively and said input terminal; a second set of impedances including third and fourth impedance arms connected between said inverting and noninverting inputs respectively and said common terminal; a third set of impedances including fifth and sixth impedance arms connected between said inverting and noninverting inputs respectively and said output terminal; each of the impedance arms of one of said sets being complex resistive-capacitive impedances and the other impedance arms of the other two sets being resistive, said impedances coacting with said differential amplifier to provide a notch filter.
Claim 2
Dependent Claim
141 words
A second-order canonical active filter comprising: input, output and common terminals; a differential amplifier having inverting and noninverting inputs, and an output, the output of the differential amplifier being connected to said output terminal; a first set of impedances including first and second impedance arms connected between said inverting and noninverting inputs respectively and said input terminal; a second set of impedances including third and fourth impedance arms connected between said inverting and noninverting inputs respectively and said common terminal; a third set of impedances including fifth and sixth impedance arms connected between said inverting and noninverting inputs respectively and said output terminal; each of the impedance arms of one of said sets being complex resistive-capacitive impedances and the other impedance arms of the other two sets being resistive, said impedances coacting with said differential amplifier to provide a notch filter.
Claim 3
Dependent Claim
56 words
A second-order canonical active filter as defined in claim 1 in which: the first arm includes a first resistor and a first capacitor connected in series; the second arm includes a second resistor and a second capacitor connected in shunt; and the third, fourth, fifth and sixth arms include third, fourth, fifth and sixth resistors respectively.
Claim 4
Dependent Claim
56 words
A second-order canonical active filter as defined in claim 1 in which: the third arm includes a first resistor and a first capacitor connected in series; the fourth arm includes a second resistor and a second capacitor connected in shunt; and the first, second, fifth and sixth arms include third, fourth, fifth and sixth resistors respectively.
Claim 5
Dependent Claim
26 words
A second-order canonical active filter as defined in claim 1 in which: the fifth arm includes a first resistor and a first capacitor connected in shunt;
Claim 6
Dependent Claim
30 words
the sixth arm includes a second resistor and a second capacitor connected in series; and the first, second, third and fourth arms include third, fourth, fifth and sixth resistors respectively.
Claim 7
Dependent Claim
30 words
the sixth arm includes a second resistor and a second capacitor connected in series; and the first, second, third and fourth arms include third, fourth, fifth and sixth resistors respectively.
Claim 8
Dependent Claim
88 words
A second-order canonical active filter comprising: input, output and common terminals; a differential amplifier having inverting and noninverting inputs, and an output, the output of the differential amplifier being connected to said output terminal; six separate impedances each being connected between a different one of said amplifier inputs and one of said terminals; both of said impedances connected to one of said terminals being resistive-capacitive, and the impedances connected to the other two terminals being resistive; the impedances coacting with the differential amplifier to provide a notch filter.
Claim 9
Dependent Claim
88 words
A second-order canonical active filter comprising: input, output and common terminals; a differential amplifier having inverting and noninverting inputs, and an output, the output of the differential amplifier being connected to said output terminal; six separate impedances each being connected between a different one of said amplifier inputs and one of said terminals; both of said impedances connected to one of said terminals being resistive-capacitive, and the impedances connected to the other two terminals being resistive; the impedances coacting with the differential amplifier to provide a notch filter.
Claim 10
Dependent Claim
42 words
A second-order canonical active filter as defined in claim 5 in which one impedance connected to said one terminal is a serially connected resistor and capacitor, and the other impedance connected to said one terminal is a shunt connected resistor and capacitor.
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) | 1979-11-23 | 1980-05-24 | 1980-11-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-11-23 | 1984-05-24 | 1984-11-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-11-23 | 1988-05-24 | 1988-11-23 | $7700.00 | Window Closed / Lapsed |