US3659121A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Constant current source
Assignee: Motorola Solutions Inc
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Filing: 1970-11-16
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Granted: 1972-04-25
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Expires: 1990-11-16
Abstract
Abstract An improved constant current source, which may provide very small current without requiring the construction of a large resistor, is disclosed. This constant current source includes a transistor having a bias source comprising a second transistor that is biased to low current conduction, the biasing resistor for the biased transistor being advantageously small.
Inventors
- 👤 Thomas M Frederiksen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 04:28
CPC Classifications
G; G05; G05F; G05F3/00; G05F3/02; G05F3/08; G05F3/10; G05F3/16; G05F3/20; G05F3/30
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
126 words
A source for a load requiring a low constant current comprising: a first transistor having base, emitter and collector electrodes, the collector and emitter of the transistor being connected in series with the load across a supply source; biasing source means connected to the base electrode of the first transistor for maintaining said transistor in a constant low current conduction stage, said biasing source means comprising a second transistor having base, emitter and collector electrodes; and means for maintaining said second transistor in a high current conduction state comprising first and second resistors connected in series with the collector and emitter of the second transistor across the supply source, the base of the second transistor being connected directly to the collector thereof through said second resistor.
Claim 2
Dependent Claim
126 words
A source for a load requiring a low constant current comprising: a first transistor having base, emitter and collector electrodes, the collector and emitter of the transistor being connected in series with the load across a supply source; biasing source means connected to the base electrode of the first transistor for maintaining said transistor in a constant low current conduction stage, said biasing source means comprising a second transistor having base, emitter and collector electrodes; and means for maintaining said second transistor in a high current conduction state comprising first and second resistors connected in series with the collector and emitter of the second transistor across the supply source, the base of the second transistor being connected directly to the collector thereof through said second resistor.
Claim 3
Dependent Claim
32 words
A current source as recited in claim 1 wherein the emitter of the first transistor and the emitter of the second transistor are connected to a common terminal of the supply source.
Claim 4
Dependent Claim
229 words
A constant current source comprising: a first and a second resistor; first and second transistors each having main electrodes and a control electrode; means for connecting said resistors in series between the main electrode of said first transistor and a first supply terminal; means for connecting a point between said resistors to the control electrode of said first transistor; means for connecting the other main electrode of said first transistor to another supply terminal; means for connecting a load which requires constant current between said first supply terminal and a first main electrode of said second transistor; means for connecting a control electrode of said second transistor to the first main electrode of said first transistor; means for connecting the other main electrode of said second transistor to the other supply terminal; a third transistor having main electrodes and a control electrode; a third and a fourth resistor; means for connecting a second load requiring constant current flow between said first terminal and the first main electrode of said third transistor; means for connecting the control electrode of said third transistor through said first resistor to said first supply terminal and through said third and second resistors to the first main electrode of said first transistor; and means to connect the second main electrode of said third transistor by way of said fourth resistor to said second supply terminal.
Claim 5
Dependent Claim
229 words
A constant current source comprising: a first and a second resistor; first and second transistors each having main electrodes and a control electrode; means for connecting said resistors in series between the main electrode of said first transistor and a first supply terminal; means for connecting a point between said resistors to the control electrode of said first transistor; means for connecting the other main electrode of said first transistor to another supply terminal; means for connecting a load which requires constant current between said first supply terminal and a first main electrode of said second transistor; means for connecting a control electrode of said second transistor to the first main electrode of said first transistor; means for connecting the other main electrode of said second transistor to the other supply terminal; a third transistor having main electrodes and a control electrode; a third and a fourth resistor; means for connecting a second load requiring constant current flow between said first terminal and the first main electrode of said third transistor; means for connecting the control electrode of said third transistor through said first resistor to said first supply terminal and through said third and second resistors to the first main electrode of said first transistor; and means to connect the second main electrode of said third transistor by way of said fourth resistor to said second supply terminal.
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) | 1975-04-25 | 1975-10-25 | 1976-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-25 | 1979-10-25 | 1980-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-25 | 1983-10-25 | 1984-04-25 | $7700.00 | Window Closed / Lapsed |