Patent US4423357A successfully refreshed from Google Patents.
US4423357A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Switchable precision current source
Assignee: International Business Machines Corp
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Filing: 1982-06-21
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Granted: 1983-12-27
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Expires: 2002-06-21
Abstract
Abstract Three-transistor, four-terminal precision current source is switchable. Current is passed between two of the terminals in the presence of a switching signal on another terminal. While switched on, the current is regulated according to a reference voltage supplied to the remaining terminal.
Inventors
- 👤 Jeffery A. Engelman
- 👤 James L. Sanford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 08:56
CPC Classifications
G; G05; G05F; G05F3/00; G05F3/02; G05F3/08; G05F3/10; G05F3/16; G05F3/20; G05F3/22
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
118 words
A switchable current source comprising: a load; power source means for supplying current; a reference voltage source means; a switching signal source means; first transistor means coupled between said power source means and said load, having a collector means and an emitter means coupled thereto, respectively; second and third transistor means coupled together in series to conduct in the same direction between said power source means to a base means of said first transistor; means for coupling said reference voltage source means to a base means of said third transistor for regulating the current therethrough; and means for coupling said switching signal source means to a base means of said second transistor means for controlling the current therethrough.
Claim 2
Dependent Claim
118 words
A switchable current source comprising: a load; power source means for supplying current; a reference voltage source means; a switching signal source means; first transistor means coupled between said power source means and said load, having a collector means and an emitter means coupled thereto, respectively; second and third transistor means coupled together in series to conduct in the same direction between said power source means to a base means of said first transistor; means for coupling said reference voltage source means to a base means of said third transistor for regulating the current therethrough; and means for coupling said switching signal source means to a base means of said second transistor means for controlling the current therethrough.
Claim 3
Dependent Claim
32 words
The invention as claimed in claim 1 wherein said switching signal source means includes fourth transistor means for translating a switching signal at one level of a switching signal at another level.
Claim 4
Dependent Claim
15 words
The invention as claimed in claim 1 wherein said load includes a light-emitting diode means.
Claim 5
Dependent Claim
25 words
The invention as claimed in claim 1 including additional circuits of the same type coupled in parallel between said load and said power source means.
Claim 6
Dependent Claim
205 words
A semiconductor current drive circuit for supplying a switchable controlled current to a load comprising, in combination: load means; power supply means for supplying current to the circuit; means for supplying a reference voltage; means for supplying a switching signal; output transistor means for supplying current to said load, said output transistor having a base means, a collector means coupled to said power supply means, and an emitter means coupled to said load means; a pair of complementary transistor means for controlling the current through said output transistor means, each of said pair of complementary transistor means having emitter means, base means, and collector means; means for coupling together the emitter means of said pair of complementary transistor means; means for coupling the collector of one of said pair of complementary transistor means to the base of said output transistor means; means for coupling the base of said one of said pair of complementary transistor means to said reference voltage supplying means; means for coupling the collector of the other one of said pair of complementary transistor means to the power supply means; and means for coupling the base of the other one of said pair of complementary transistor means to switching signal supplying means.
Claim 7
Dependent Claim
205 words
A semiconductor current drive circuit for supplying a switchable controlled current to a load comprising, in combination: load means; power supply means for supplying current to the circuit; means for supplying a reference voltage; means for supplying a switching signal; output transistor means for supplying current to said load, said output transistor having a base means, a collector means coupled to said power supply means, and an emitter means coupled to said load means; a pair of complementary transistor means for controlling the current through said output transistor means, each of said pair of complementary transistor means having emitter means, base means, and collector means; means for coupling together the emitter means of said pair of complementary transistor means; means for coupling the collector of one of said pair of complementary transistor means to the base of said output transistor means; means for coupling the base of said one of said pair of complementary transistor means to said reference voltage supplying means; means for coupling the collector of the other one of said pair of complementary transistor means to the power supply means; and means for coupling the base of the other one of said pair of complementary transistor means to switching signal supplying means.
Claim 8
Dependent Claim
72 words
The invention as claimed in claim 5 wherein said means for supplying a switching signal comprises switching transistor means having a base means for receiving a signal referenced to a common return potential of said power supply means, an emitter means coupled to said common return potential, and a collector means coupled to supply a switching signal referenced to the base of said other one of said pair of complementary transistor means.
Claim 9
Dependent Claim
25 words
The invention as claimed in claim 6 including voltage divider means coupled between said power supply means and said collector means of said switching transistor.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-12-26 | 1987-06-27 | 1987-12-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-26 | 1991-06-27 | 1991-12-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-26 | 1995-06-27 | 1995-12-27 | $7700.00 | Window Closed / Lapsed |