US3602799A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Temperature stable constant current source
Assignee: Westinghouse Electric Corp
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Filing: 1970-06-24
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Granted: 1971-08-31
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Expires: 1990-06-24
Abstract
Abstract An ultrastable high-speed constant DC current source for generating a precise reference voltage in other apparatus such as a high-speed analogue to digital converter. A continuous constant load current is selectively switched between two current paths, one of which comprises an output load across which said reference voltage is developed. A high-speed digitally controlled driver circuit including a differential amplifier configuration controls the flow of the constant current selectively through one of two hot carrier diodes. The diodes serve as electronic switches from the constant current source which comprises an operational amplifier connected in a feedback loop including a Darlington transistor configuration and controlled by an externally applied input reference voltage and an error signal developed by the flow of said load current across a temperature compensated resistor.
Inventors
- 👤 Francisco J Guillen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 13:46
CPC Classifications
G; G05; G05F; G05F1/00; G05F1/10; G05F1/46; G05F1/56; G05F3/00; G05F3/02; G05F3/08; G05F3/10; G05F3/16; G05F3/20; G05F3/22; G05F3/222; G05F3/225
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
221 words
Apparatus for delivering a constant current to a load from a source of supply voltage over a relatively wide temperature range of operation, comprising in combination: electronic switch means having a first and a second current switch including circuit means coupling said first current switch to one side of said load, said load having its opposite side coupled to said source of supply voltage; driver circuit means operated in accordance with at least one control signal applied thereto and including an electronic circuit coupled to said second current switch, said electronic circuit being operated by said control signal to cause said second current switch to become selectively nonconductive and conductive while causing said first current switch to become conductive and nonconductive and thereby switch substantially all of said constant current respectively to said first or second current switch; a reference voltage source providing an output of reference voltage; and a constant current source coupled in series between said electronic switch means and said source of supply voltage and additionally including circuit means coupled to said reference voltage source and being responsive to said reference voltage to generate said constant current of a predetermined magnitude in response to the magnitude of said reference voltage, said constant current thereby being adapted to flow continuously either through said first or said second current switch.
Claim 2
Dependent Claim
221 words
Apparatus for delivering a constant current to a load from a source of supply voltage over a relatively wide temperature range of operation, comprising in combination: electronic switch means having a first and a second current switch including circuit means coupling said first current switch to one side of said load, said load having its opposite side coupled to said source of supply voltage; driver circuit means operated in accordance with at least one control signal applied thereto and including an electronic circuit coupled to said second current switch, said electronic circuit being operated by said control signal to cause said second current switch to become selectively nonconductive and conductive while causing said first current switch to become conductive and nonconductive and thereby switch substantially all of said constant current respectively to said first or second current switch; a reference voltage source providing an output of reference voltage; and a constant current source coupled in series between said electronic switch means and said source of supply voltage and additionally including circuit means coupled to said reference voltage source and being responsive to said reference voltage to generate said constant current of a predetermined magnitude in response to the magnitude of said reference voltage, said constant current thereby being adapted to flow continuously either through said first or said second current switch.
Claim 3
Dependent Claim
22 words
The invention as defined by claim 1 wherein said first and second current switch comprises a first and a second semiconductive diode.
Claim 4
Dependent Claim
20 words
The invention as defined by claim 2 wherein said first and second semiconductor diodes are comprised of Schottky barrier diodes.
Claim 5
Dependent Claim
221 words
The invention as defined by claim 1 wherein said constant current source comprises: DC amplifier means including a feedback control loop and having first and second input terminals and an output terminal, being operable to provide an output signal which is a function of the signal difference between signals respectively applied to said first and second input terminal; first circuit means coupling said first input terminal to said reference voltage; second circuit means coupling said source of supply voltage to said first input terminal; first feedback means comprising at least one transistor having an input electrode and a first and second output electrode, including circuit means coupling said output terminal of said DC amplifier means to said input electrode, said first output electrode to said electronic switch means, and said second output terminal to said second input terminal; and second feedback means coupling said second output electrode of said at least one transistor and said second input terminal of said DC amplifier means to said source of supply voltage, whereby said first and second feedback means defines said feedback control loop whereby a voltage is produced across said second feedback means and is applied to said second input terminal for causing a substantially constant current flow between said switch means and said second output electrode of said at least one transistor.
Claim 6
Dependent Claim
29 words
The invention as defined by claim 4 wherein said first feedback means additionally comprises a second transistor coupled to said at least one transistor in a Darlington circuit configuration.
Claim 7
Dependent Claim
23 words
The invention as defined by claim 5 wherein said first and second current switch comprises a first and a second Schottky barrier diode.
Claim 8
Dependent Claim
98 words
The invention as defined by claim 4 wherein said first feedback means comprises a first and a second transistor each having an input electrode and a first and second output electrode and including circuit means commonly coupling said first output electrodes together to said switch means, said input electrode of said first transistor to said output terminal of said DC amplifier means, said second output electrode of said first transistor to said input electrode of said second transistor, and said second output electrode of said second transistor to said third circuit means providing thereby a Darlington circuit configuration.
Claim 9
Dependent Claim
47 words
The invention as defined by claim 7 wherein said switch means comprises a pair of hot carrier diodes and wherein one of said pair of diodes is directly connected between said load and said common coupling of said first output electrodes of said first and second transistor.
Claim 10
Dependent Claim
23 words
The invention as defined by claim 8 wherein said first and second circuit means and said second feedback means each comprises resistor means.
Claim 11
Dependent Claim
39 words
The invention as defined by claim 1 wherein said reference voltage source comprises a DC voltage regulator circuit including means for selectively adjusting the magnitude of said reference voltage thereby controlling said substantially constant current supplied to said load.
Claim 12
Dependent Claim
70 words
The invention as defined by claim 1 wherein said driver means comprises a differential amplifier having a first and a second input circuit adapted to be coupled respectively to and operated by a binary input signal and the complement thereof and an output circuit coupled to said second current switch of said switch means, said output circuit being rendered selectively operative to control current flow in said second current switch.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-08-30 | 1975-03-01 | 1975-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-30 | 1979-03-01 | 1979-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-30 | 1983-03-01 | 1983-08-31 | $7700.00 | Window Closed / Lapsed |