Patent US4378521A successfully refreshed from Google Patents.
US4378521A
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Active zener diode substitute circuit
Assignee: Hughes Missile Systems Co
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Filing: 1981-10-15
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Granted: 1983-03-29
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Expires: 2001-10-15
Abstract
Abstract A circuit which performs regulator or limiter functions at current and voltage levels below the operating ranges of conventional zener diodes. The output of an op amp is connected through a diode to a main input terminal which may be connected between a power source and one end of a load resistor. A first current limiting resistor connects the main input terminal to the inverting input of the op amp. A second current limiting resistor connects the non-inverting input of the op amp to the wiper terminal of a potentiometer which permits adjustment of a simulated zener voltage V z . A pair of supply voltage terminals of the op amp are connected to voltages V cc and V ee , respectively. A pair of fixed terminals of the potentiometer are also connected to voltages V cc and V ee , respectively. The simulated zener voltage V z may be positive or negative, and may be adjusted to any value within limits determined by voltages V cc and V ee , the op amp saturation voltages, the current sinking capability of the op amp, and the voltage drop across the diode.
Inventors
- 👤 Richard W. Thorpe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 11:57
CPC Classifications
H; H03; H03K; H03K5/00; H03K5/01; H03K5/08
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
178 words
An active zener diode substitute circuit comprising: a main input terminal connectable between a power source and one end of a load resistor; an operational amplifier having an inverting input terminal, a non-inverting input terminal, an output terminal, a first supply voltage terminal connectable to a source of a supply voltage V cc and a second supply voltage terminal connectable to a source of a supply voltage V ee ; a diode having an anode and a cathode and connected between the output terminal of the operational amplifier and the main input terminal; a first resistor having one end connected to the inverting input terminal of the operational amplifier and another end connected to the main input terminal; a second resistor having one end connected to the non-inverting input terminal of the operational amplifier; and a potentiometer having a wiper terminal connected to the other end of the second resistor, a first fixed terminal connectable to the source of supply voltage V cc and a second fixed terminal connectable to the source of supply voltage V ee .
Claim 2
Dependent Claim
178 words
An active zener diode substitute circuit comprising: a main input terminal connectable between a power source and one end of a load resistor; an operational amplifier having an inverting input terminal, a non-inverting input terminal, an output terminal, a first supply voltage terminal connectable to a source of a supply voltage V cc and a second supply voltage terminal connectable to a source of a supply voltage V ee ; a diode having an anode and a cathode and connected between the output terminal of the operational amplifier and the main input terminal; a first resistor having one end connected to the inverting input terminal of the operational amplifier and another end connected to the main input terminal; a second resistor having one end connected to the non-inverting input terminal of the operational amplifier; and a potentiometer having a wiper terminal connected to the other end of the second resistor, a first fixed terminal connectable to the source of supply voltage V cc and a second fixed terminal connectable to the source of supply voltage V ee .
Claim 3
Dependent Claim
35 words
A circuit according to claim 1 wherein the anode of the diode is connected to the main input terminal and the cathode of the diode is connected to the output terminal of the operational amplifier.
Claim 4
Dependent Claim
35 words
A circuit according to claim 1 wherein the cathode of the diode is connected to the main input terminal and the anode of the diode is connected to the output terminal of the operational amplifier.
Claim 5
Dependent Claim
25 words
A circuit according to claim 1 wherein the operational amplifier is an integrated circuit having an input stage including a plurality of field effect transistors.
Claim 6
Dependent Claim
14 words
A circuit according to claim 1 wherein the diode is a PN junction diode.
Claim 7
Dependent Claim
17 words
A circuit according to claim 1 wherein the diode has a breakdown voltage substantially above five volts.
Claim 8
Dependent Claim
18 words
A circuit according to claim 1 wherein the other end of the load resistor is connected to ground.
Claim 9
Dependent Claim
24 words
A circuit according to claim 1 wherein the other end of the load resistor is connected to a source of positive or negative voltage.
Claim 10
Dependent Claim
39 words
A circuit according to claim 1 wherein the operational amplifier, diode, first and second resistors, potentiometer, and supply voltages V cc and V ee are selected so that the circuit can regulate at a current level below one milliamp.
Claim 11
Dependent Claim
39 words
A circuit according to claim 1 wherein the operational amplifier, diode, first and second resistors, potentiometer, and supply voltages V cc and V ee are selected so that the circuit can supply a reference voltage less than three volts.
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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) | 1986-03-28 | 1986-09-27 | 1987-03-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-03-28 | 1990-09-27 | 1991-03-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-03-28 | 1994-09-27 | 1995-03-29 | $7700.00 | Window Closed / Lapsed |