US4680535A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stable current source
Assignee: Harris Corp
•
Filing: 1986-01-29
•
Granted: 1987-07-14
•
Expires: 2006-01-29
Abstract
Abstract A highly stable current source which is protected against high voltage overloads, comprising a loop circuit in which the current of known magnitude Iref passes through a scaler resistor to develop a voltage drop thereacross, which is connected with a floating potential in a loop circuit. A differential amplifier is coupled to differentially measure the voltages across the scaler resistor and the floating potential, and provides an output indicative thereof, which determines Iref. In this arrangement, the voltage drop across the scaler resistor equals the voltage drop across the floating potential, and the current Iref through the scaler resistor remains constant at a known magnitude. Embodiments of both positive and negative current generating circuits are disclosed.
Inventors
- 👤 Shlomo S. Talmor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 04:55
CPC Classifications
G; G05; G05F; G05F1/00; G05F1/10; G05F1/46; G05F1/56; G05F1/561; Y; Y10; Y10S; Y10S323/00; Y10S323/907
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
104 words
A stable current source circuit for supplying a current of known magnitude Iref, comprising a scaler resistor having the current of known magnitude Iref passing therethrough to develop a voltage drop thereacross, a floating potential circuit connected to said scaler resistor in a loop circuit, and a differential amplifier coupled to differentially measure the voltages across said scaler resistor and said floating potential circuit and provide an output indicative thereof which determines Iref, such that the voltage drop across the scaler resistor equals the voltage drop across the floating potential and the current Iref through said scaler resistor remains constant at a known magnitude.
Claim 2
Dependent Claim
104 words
A stable current source circuit for supplying a current of known magnitude Iref, comprising a scaler resistor having the current of known magnitude Iref passing therethrough to develop a voltage drop thereacross, a floating potential circuit connected to said scaler resistor in a loop circuit, and a differential amplifier coupled to differentially measure the voltages across said scaler resistor and said floating potential circuit and provide an output indicative thereof which determines Iref, such that the voltage drop across the scaler resistor equals the voltage drop across the floating potential and the current Iref through said scaler resistor remains constant at a known magnitude.
Claim 3
Dependent Claim
44 words
A stable current source circuit as claimed in claim 1, including an inverting amplifier coupled to the output of said differential amplifier for providing enhanced voltage compliance and for isolation in the event of the accidental application of a high voltage to the circuit.
Claim 4
Dependent Claim
25 words
A stable current source circuit as claimed in claim 2, said floating potential comprising a steady current source I and a floating potential resistor Rfp.
Claim 5
Dependent Claim
61 words
A stable current source circuit as claimed in claim 3, wherein said inverting amplifier is a transistor amplifier having a transistor with an emitter, a base and a collector, and further including a voltage follower circuit coupled to said floating potential resistor to prevent the current through said floating potential resistor from flowing to the collector of said transistor inverting amplifier.
Claim 6
Dependent Claim
34 words
A stable current source circuit as claimed in claim 4, wherein the output of the stable current source includes a blocking diode which provides reverse high voltage overload protection for the current source circuit.
Claim 7
Dependent Claim
33 words
A stable current source circuit as claimed in claim 5, said steady current source including an MOS amplifier, and said differential and inverting amplifiers and said voltage follower circuit also comprising MOS circuits.
Claim 8
Dependent Claim
23 words
A stable current source circuit as claimed in claim 6, said steady current source including a Zener diode for providing temperature compensation therefor.
Claim 9
Dependent Claim
44 words
A stable current source circuit as claimed in claim 7, said loop circuit further comprising two clamping diodes coupled between the circuit loop and ground which provide high voltage overload for the loop circuit by clamping the anodes thereof to a given positive voltage.
Claim 10
Dependent Claim
53 words
A stable current source circuit as claimed in claim 7, said loop circuit further comprising two clamping diodes, each having an anode and a cathode, coupled between the circuit loop and a negative voltage which provide high voltage overload for the loop circuit by clamping the cathodes thereof to a given negative voltage.
Claim 11
Dependent Claim
25 words
A stable current source circuit as claimed in claim 1, said floating potential comprising a steady current source I and a floating potential resistor Rfp.
Claim 12
Dependent Claim
54 words
A stable current source circuit as claimed in claim 1, further including an inverting transistor amplifier coupled to the output of said differential amplifier, and a voltage follower circuit coupled to said floating potential resistor to prevent the current through said floating potential resistor from flowing to the collector of said inverting transistor amplifier.
Claim 13
Dependent Claim
35 words
A stable current source circuit as claimed in claim 1, wherein the output of the stable current source includes a blocking diode which provides reverse high voltage overload protection for the stable current source circuit.
Claim 14
Dependent Claim
44 words
A stable current source circuit as claimed in claim 1, said loop circuit further comprising two clamping diodes coupled between the circuit loop and ground which provide high voltage overload for the loop circuit by clamping the anodes thereof to a given positive voltage.
Claim 15
Dependent Claim
53 words
A stable current source circuit as claimed in claim 1, said loop circuit further comprising two clamping diodes, each having an anode and a cathode, coupled between the circuit loop and a negative voltage which provide high voltage overload for the loop circuit by clamping the cathodes thereof to a given negative voltage.
Claim 16
Dependent Claim
53 words
A stable current source circuit as claimed in claim 1, said loop circuit further comprising two clamping diodes, each having an anode and a cathode, coupled between the circuit loop and a positive voltage, which provide high voltage overload for the loop circuit by clamping the anodes thereof to a given positive voltage.
References Cited (Backward Citations)
US29619A
Cited
US2716729A
Cited
US3536986A
Cited
US3573595A
Cited
US3675122A
Cited
USRE29619E
Cited
US3787734A
Cited
US3784844A
Cited
US3899692A
Cited
US3979663A
Cited
US4150309A
Cited
US4104575A
Cited
US4112346A
Cited
US4251743A
Cited
US4240024A
Cited
US4570115A
Cited
US4504882A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-07-13 | 1991-01-12 | 1991-07-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-07-13 | 1995-01-12 | 1995-07-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-07-13 | 1999-01-12 | 1999-07-14 | $7700.00 | Window Closed / Lapsed |