US3701059A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Remote controlled, adjustable bandwidth low pass filter
Assignee: United States Department of the Navy
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Filing: 1971-04-16
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Granted: 1972-10-24
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Expires: 1991-04-16
Abstract
Abstract A bandwidth controlled, low pass filter circuit having a resistor, capacitor, voltage follower amplifier, and an insulated gate, metallic oxide semiconductor, field effect transistor utilized as a switch, in which the transistor and the resistor, together, provide the effective circuit filter resistance, and the bandwidth is controlled by the transistor gate pulse frequency and pulse width. The use of several such filters as a filter bank is also disclosed.
Inventors
- 👤 Reuben E Nyswander
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:42
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/126
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
170 words
A low pass filter comprising: resistive means for providing electrical resistance, including a resistor and a transistor switch wherein said resistor is directly connected to said transistor switch and said transistor switch is an insulated gate, metallic oxide semiconductor, field effect transistor having a source terminal, a drain terminal, a bias terminal, and an insulated gate terminal, wherein said bias terminal is coupled to a constant direct current voltage, and said insulated gate terminal is coupled to a control signal which controls the mode of said switch; capacitive means for accepting and retaining an electrical charge, and providing an electrical output; wherein said capacitive means is a capacitor coupled to the end of said resistor opposite the end coupled to said transistor, and the combination is coupled to an electrical signal providing means such that the electrical charge on the capacitive means is a function of the electrical signal; and wherein said source terminal is coupled to said signal providing means and said drain terminal is coupled to said resistor.
Claim 2
Dependent Claim
170 words
A low pass filter comprising: resistive means for providing electrical resistance, including a resistor and a transistor switch wherein said resistor is directly connected to said transistor switch and said transistor switch is an insulated gate, metallic oxide semiconductor, field effect transistor having a source terminal, a drain terminal, a bias terminal, and an insulated gate terminal, wherein said bias terminal is coupled to a constant direct current voltage, and said insulated gate terminal is coupled to a control signal which controls the mode of said switch; capacitive means for accepting and retaining an electrical charge, and providing an electrical output; wherein said capacitive means is a capacitor coupled to the end of said resistor opposite the end coupled to said transistor, and the combination is coupled to an electrical signal providing means such that the electrical charge on the capacitive means is a function of the electrical signal; and wherein said source terminal is coupled to said signal providing means and said drain terminal is coupled to said resistor.
Claim 3
Dependent Claim
34 words
The filter of claim 1 wherein said filter further comprises an amplifier coupled to the junction of said capacitor and said resistor for amplifying the voltage on said capacitor and providing the filter output.
Claim 4
Dependent Claim
61 words
The filter of claim 2 wherein the half-power bandwidth of said filter is: F D/2 pi RC(D + T) wherein R is the resistance of said resistor, C is the capacitance of said capacitor, D is the period of time said transistor is in its conductive mode, and T is the period of time said transistor is in its resistive mode.
Claim 5
Dependent Claim
51 words
The filter of claim 3 wherein: said transistor is an NPN field effect transistor; and the voltage of said control signal is approximately equal to said constant direct current voltage during said period of time T, and more positive than said constant direct current voltage during said period of time D.
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) | 1975-10-24 | 1976-04-24 | 1976-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-24 | 1980-04-24 | 1980-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-24 | 1984-04-24 | 1984-10-24 | $7700.00 | Window Closed / Lapsed |