Patent US737223A successfully refreshed from Google Patents.
US4200898A
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US
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Current limiter
Assignee: United States Department of the Navy
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Filing: 1978-06-19
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Granted: 1980-04-29
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Expires: 1998-06-19
Abstract
Abstract A current limiter for an a.c. circuit having two FET's connected source to drain. The FET's are biased for symmetrical bipolar operation with source resistors for self-biasing. In operation one FET operates as a source follower and the other as a current source.
Inventors
- 👤 James P. Thompson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 17:04
CPC Classifications
H; H02; H02H; H02H9/00; H02H9/02; H02H9/025
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
145 words
A current limiter for an a.c. circuit comprising: (a) a first field effect transistor connected in series to the line side of said a.c. circuit; (b) a second field effect transistor connected in cascode to said first field effect transistor and in series to the load side of said a.c. circuit; (c) a plurality of resistors connected in series between the line side and the load side of said a.c. circuit to form a voltage divider network, the gates of said field effect transistors being connected at different points, respectively, of said voltage divider network; and (d) means for bypassing the portion of said voltage divider network between the gate and the terminal of each of said field effect transistors connected to said a.c. circuit so that said field effect transistors operate interchangeably as a current source depending upon the polarity of the applied voltage.
Claim 2
Dependent Claim
145 words
A current limiter for an a.c. circuit comprising: (a) a first field effect transistor connected in series to the line side of said a.c. circuit; (b) a second field effect transistor connected in cascode to said first field effect transistor and in series to the load side of said a.c. circuit; (c) a plurality of resistors connected in series between the line side and the load side of said a.c. circuit to form a voltage divider network, the gates of said field effect transistors being connected at different points, respectively, of said voltage divider network; and (d) means for bypassing the portion of said voltage divider network between the gate and the terminal of each of said field effect transistors connected to said a.c. circuit so that said field effect transistors operate interchangeably as a current source depending upon the polarity of the applied voltage.
Claim 3
Dependent Claim
60 words
A current limiter as recited in claim 1 wherein said bypassing means comprises a low current diode for each of said first and second field effect transistors, said low current diode having the anode connected to the gate and the cathode connected to the terminal of said first and second field effect transistors which is connected to said a.c. circuit.
Claim 4
Dependent Claim
36 words
A current limiter as recited in claim 2 further comprising means for self-biasing said first and second field effect transistors, said self-biasing means being connected in series between one terminal of each and said a.c. circuit.
Claim 5
Dependent Claim
33 words
A current limiter as recited in claim 3 wherein said self-biasing means comprises a resistor having a value much smaller than that of any one of said resistors of said voltage divider network.
Claim 6
Dependent Claim
138 words
A current limiter for an a.c. circuit comprising: (a) a first solid state device having symmetrical characteristics connected in series to the line side of said a.c. circuit; (b) a second solid state device having symmetrical characteristics, said second solid state device being connected in cascode to said first solid state device and being connected in series to the load side of said a.c. circuit; and (c) means connected between the line and the load sides of said a.c. circuit for biasing said first and said second solid state devices so that said first and said second solid state devices act interchangeably as a current source and a unity gain buffer depending upon the polarity of the applied voltage so that the current of said a.c. circuit is limited by the saturation current of said solid state devices.
Claim 7
Dependent Claim
138 words
A current limiter for an a.c. circuit comprising: (a) a first solid state device having symmetrical characteristics connected in series to the line side of said a.c. circuit; (b) a second solid state device having symmetrical characteristics, said second solid state device being connected in cascode to said first solid state device and being connected in series to the load side of said a.c. circuit; and (c) means connected between the line and the load sides of said a.c. circuit for biasing said first and said second solid state devices so that said first and said second solid state devices act interchangeably as a current source and a unity gain buffer depending upon the polarity of the applied voltage so that the current of said a.c. circuit is limited by the saturation current of said solid state devices.
Claim 8
Dependent Claim
54 words
A current limiter as recited in claim 5 wherein said first solid state device comprises a first field effect transistor having one terminal connected in series with the line side of said a.c. circuit, having the gate connected to said biasing means, and having the second terminal connected to said second solid state device.
Claim 9
Dependent Claim
54 words
A current limiter as recited in claim 6 wherein said second solid state device comprises a second field effect transistor having one terminal connected to said first solid state device, having the gate connected to said biasing means, and having the second terminal connected in series with the load side of said a.c. circuit.
Claim 10
Dependent Claim
38 words
A current limiter as recited in claim 5 further comprising an intermediate solid state device having symmetrical characteristics connected in cascode between said first and said second solid state devices to provide current limiting at greater applied voltages.
Claim 11
Dependent Claim
57 words
A current limiter as recited in claim 8 wherein said first solid state device comprises a first field effect transistor having one terminal connected in series with the line side of said a.c. circuit, having the gate connected to said biasing means, and having the second terminal connected to one side of said intermediate solid state device.
Claim 12
Dependent Claim
58 words
A current limiter as recited in claim 9 wherein said second solid state device comprises a second field effect transistor having one terminal connected to the other side of said intermediate solid state device, having the gate connected to said biasing means, and having the second terminal connected in series with the line side of said a.c. circuit.
Claim 13
Dependent Claim
45 words
A current limiter as recited in claim 10 wherein said intermediate solid state device comprises at least one intermediate field effect transistor having the terminals connected in series between said first and second field effect transistors, and having the gate connected to said biasing means.
References Cited (Backward Citations)
JPS4424965B1
Cited
US3521087A
Cited
US3603811A
Cited
US3760284A
Cited
US3656025A
Cited
US3916220A
Cited
US3967187A
Cited
USB501181I5
Cited
US3925718A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-04-29 | 1983-10-29 | 1984-04-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-04-29 | 1987-10-29 | 1988-04-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-04-29 | 1991-10-29 | 1992-04-29 | $7700.00 | Window Closed / Lapsed |