US3604947A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Variable filter device
Assignee: Aerojet Rocketdyne Inc
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Filing: 1969-06-24
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Granted: 1971-09-14
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Expires: 1989-06-24
Abstract
Abstract The present invention relates to electrical circuit apparatus capable of providing sampled integration of an electric signal. According to the present invention, an integrator filter is provided having at least one capacitor stage. Each stage includes a capacitor in series with an electronic switch, such as a fieldeffect transistor capable of being switched at a desired frequency.
Inventors
- 👤 Steven H Puthuff
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:38
CPC Classifications
H; H03; H03K; H03K9/00; H03K9/04; G; G01; G01R; G01R23/00; G01R27/00; G01R27/28; G01R27/32; G06; G06G; G06G7/00; G06G7/12; G06G7/18; G06G7/184; G11; G11C; G11C27/00; G11C27/02; G11C27/024; H03C; H03C1/00; H03H; H03H19/00; H03H19/002
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
119 words
A variable filter, comprising a signal terminal pair; a resistor; an output terminal pair; means to connect one end of said resistor to a first terminal of said signal terminal pair; means to connect the other end of said resistor to a first terminal of said output terminal pair; a capacitor; means to connect one end of said capacitor to the first terminal of said output terminal pair; bivalued resistance means; means to connect one end of said resistance means to the other end of said capacitor; means to connect together the second terminals of said signal and output terminal pairs and the other end of said resistance means; and means to switch said resistance means between its values.
Claim 2
Dependent Claim
119 words
A variable filter, comprising a signal terminal pair; a resistor; an output terminal pair; means to connect one end of said resistor to a first terminal of said signal terminal pair; means to connect the other end of said resistor to a first terminal of said output terminal pair; a capacitor; means to connect one end of said capacitor to the first terminal of said output terminal pair; bivalued resistance means; means to connect one end of said resistance means to the other end of said capacitor; means to connect together the second terminals of said signal and output terminal pairs and the other end of said resistance means; and means to switch said resistance means between its values.
Claim 3
Dependent Claim
13 words
The filter of claim 1 wherein said resistance means comprises a field-effect transistor.
Claim 4
Dependent Claim
14 words
The filter of claim 1 wherein said switch means comprises a bistable state circuit.
Claim 5
Dependent Claim
12 words
The filter of claim 1 wherein said switch means comprises a flip-flop.
Claim 6
Dependent Claim
26 words
The filter of claim 1 in which said switch means operates at a rate equivalent to the frequency of the signal at said signal terminal pair.
Claim 7
Dependent Claim
40 words
The filter of claim 1 in which the time constant of the filter is sufficiently high for one value of said resistance means to permit said capacitor to retain charge over a cycle of energization of said signal terminal pair.
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) | 1974-09-13 | 1975-03-15 | 1975-09-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-13 | 1979-03-15 | 1979-09-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-13 | 1983-03-15 | 1983-09-14 | $7700.00 | Window Closed / Lapsed |