Patent US3983504A successfully refreshed from Google Patents.
US3983504A
Expired / Lapsed
US
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Active filter
Assignee: Individual
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Filing: 1975-11-21
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Granted: 1976-09-28
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Expires: 1995-11-21
Abstract
Abstract An improved filtering circuit connected to the inverting terminal of an operational amplifier having connected in parallel a first resistor and three series capacitors. Two series resistors are connected in parallel with the center capacitor and the junction between the two series resistor is connected to a fixed potential.
Inventors
- 👤 Franklin Moy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 20:59
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/126
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
101 words
In an active filter having an operational amplifier means with an inverting input terminal, a noninverting input terminal and an output terminal and a filtering means connected between said output terminal and said inverting input terminal, the improved filtering means comprising: a first resistor means; a first, second and third capacitor means connected in series and said series connected capacitor means being connected in parallel with said first resistive means; a second and third resistive means connected in parallel with said second capacitive means; and the junction point of said second and third resistive means being connected to a fixed potential.
Claim 2
Dependent Claim
101 words
In an active filter having an operational amplifier means with an inverting input terminal, a noninverting input terminal and an output terminal and a filtering means connected between said output terminal and said inverting input terminal, the improved filtering means comprising: a first resistor means; a first, second and third capacitor means connected in series and said series connected capacitor means being connected in parallel with said first resistive means; a second and third resistive means connected in parallel with said second capacitive means; and the junction point of said second and third resistive means being connected to a fixed potential.
Claim 3
Dependent Claim
24 words
The active filter of claim 1 wherein said second and third resistive means are a potentiometer having its wiper connected to said fixed potential.
Claim 4
Dependent Claim
23 words
The active filter of claim 1 wherein said filtering means includes a fourth capacitive means connected in parallel with said first resistive means.
Claim 5
Dependent Claim
19 words
The active filter of claim 1 wherein said first, second and third capacitive means are of the same value.
Claim 6
Dependent Claim
23 words
The active filter of claim 1 wherein said first resistive means is six times the sum of said second and third resistive means.
Claim 7
Dependent Claim
103 words
In an active filter having an operational amplifier with an inverting input terminal, a noninverting input terminal and an output terminal and a filtering means connected between the input of the active filter and said inverting input terminal, the improved filtering means comprises: a first resistor means; a first, second and third capacitor means connected in series and said series connected capacitor means being connected in parallel with said first resistive means; a second and third resistive means connected in parallel with said second capacitive means; and the junction point of said second and third resistive means being connected to a fixed potential.
Claim 8
Dependent Claim
103 words
In an active filter having an operational amplifier with an inverting input terminal, a noninverting input terminal and an output terminal and a filtering means connected between the input of the active filter and said inverting input terminal, the improved filtering means comprises: a first resistor means; a first, second and third capacitor means connected in series and said series connected capacitor means being connected in parallel with said first resistive means; a second and third resistive means connected in parallel with said second capacitive means; and the junction point of said second and third resistive means being connected to a fixed potential.
Claim 9
Dependent Claim
24 words
The active filter of claim 6 wherein said second and third resistive means are a potentiometer having its wiper connected to said fixed potential.
Claim 10
Dependent Claim
23 words
The active filter of claim 6 wherein said first resistive means is six times the sum of said second and third resistive means.
Claim 11
Dependent Claim
19 words
The active filter of claim 6 wherein said first, second and third capacitive means are of the same value.
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 |