US3729685A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Self-compensated low voltage operational amplifier
Assignee: Motorola Solutions Inc
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Filing: 1971-01-28
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Granted: 1973-04-24
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Expires: 1991-01-28
Abstract
Abstract A self-compensated low voltage amplifier is provided having first, second and third transistors direct current coupled together. The first and third transistors are of a first conductivity type and the second transistor is of an opposite conductivity type. A source of supply voltage is coupled to the transistors causing them to develop operative bias voltages at the electrodes. A diode is coupled from the emitter of the third transistor to the base of the second transistors and is reverse biased by the bias voltages at the electrodes to provide a capacitive reactance between the third transistor emitter electrode and the second transistor base electrode. This capacitive reactance acts to provide a negative feedback path to the second transistor to stabilize the amplifier and prevent oscillation.
Inventors
- 👤 D Linder
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 03:56
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/08; H03F1/083; H03F1/34
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
127 words
A transistor operational amplifier including in combination; a first transistor of a first conductivity type, a second transistor of an opposite conductivity type direct current coupled to said first transistor, a third transistor of the first conductivity type direct current coupled to said second transistor, said transistors each having base, emitter and collector electrodes, supply voltage means coupled to said transistors, said transistors developing bias voltages at said electrodes in response to the supply voltage, and diode means direct current coupled from said third transistor to said second transistor and reverse biased by the bias voltages thereat, said diode means when reverse biased developing a capacitive reactance thereacross, said capacitive reactance acting to provide a negative feedback path to said second transistor to stabilize said operational amplifier.
Claim 2
Dependent Claim
127 words
A transistor operational amplifier including in combination; a first transistor of a first conductivity type, a second transistor of an opposite conductivity type direct current coupled to said first transistor, a third transistor of the first conductivity type direct current coupled to said second transistor, said transistors each having base, emitter and collector electrodes, supply voltage means coupled to said transistors, said transistors developing bias voltages at said electrodes in response to the supply voltage, and diode means direct current coupled from said third transistor to said second transistor and reverse biased by the bias voltages thereat, said diode means when reverse biased developing a capacitive reactance thereacross, said capacitive reactance acting to provide a negative feedback path to said second transistor to stabilize said operational amplifier.
Claim 3
Dependent Claim
39 words
The transistor operational amplifier of claim 1 wherein said first transistor collector electrode is direct current coupled to said second transistor base electrode, and said second transistor collector electrode is direct current coupled to said third transistor base electrode.
Claim 4
Dependent Claim
25 words
The transistor operational amplifier of claim 2 wherein said diode means is coupled from said third transistor emitter electrode to said second transistor base electrode.
Claim 5
Dependent Claim
22 words
The operational amplifier of claim 3 wherein said diode means is a junction diode having a capacitance proportional to said junction size.
Claim 6
Dependent Claim
25 words
The operational amplifier of claim 4 wherein said junction diode capacitance is further variable in relation to the magnitude of said reverse bias applied thereto.
Claim 7
Dependent Claim
116 words
A transistor amplifier including in combination; first, second and third transistors direct current coupled together in cascade, said first and third transistors being of a first conductivity type and said second transistor being of an opposite conductivity type, each of said transistors having base, emitter and collector electrodes, supply voltage means coupled to said transistors, said transistors developing bias voltages at said electrodes in response to the voltage supplied thereto, diode means coupled from said emitter electrode of said third transistor to the base electrode of said second transistor and reverse biased by the bias voltages thereat for providing a capacitive reactance therebetween and a negative feedback path to said second transistor to stabilize said amplifier.
Claim 8
Dependent Claim
116 words
A transistor amplifier including in combination; first, second and third transistors direct current coupled together in cascade, said first and third transistors being of a first conductivity type and said second transistor being of an opposite conductivity type, each of said transistors having base, emitter and collector electrodes, supply voltage means coupled to said transistors, said transistors developing bias voltages at said electrodes in response to the voltage supplied thereto, diode means coupled from said emitter electrode of said third transistor to the base electrode of said second transistor and reverse biased by the bias voltages thereat for providing a capacitive reactance therebetween and a negative feedback path to said second transistor to stabilize said amplifier.
Claim 9
Dependent Claim
102 words
The transistor amplifier of claim 6 further including a first collector resistor coupled from said first transistor collector to the supply voltage means, and a second collector transistor coupled from said second transistor collector to a reference potential, said first collector resistor being coupled to said second tRansistor base and emitter electrodes for providing a bias voltage thereto which varies in accordance with the current variation of said first stage, said second transistor collector resistor being coupled to said third transistor base and emitter electrodes for supplying a bias voltage thereto which varies in accordance with the current of said second transistor.
Claim 10
Dependent Claim
28 words
The transistor amplifier of claim 7 wherein said diode means is a junction diode, said junction diode when reverse biased having a capacitance proportional to the junction size.
Claim 11
Dependent Claim
124 words
An operational amplifier including in combination; a plurality of transistor stages direct current coupled together in cascade and having an input and output terminal, said stages being operative to provide at least 180* phase shift for signals coupled thereto with said phase shift increasing with increasing signal frequency, feedback circuit means connected from said output terminal to said input terminal, supply voltage means coupled to said stages for supplying bias voltages thereto, and diode means direct current coupled from one stage to a previous stage and reverse biased by the bias voltages thereat, said diode means when reverse biased developing a capacitive reactance thereacross, said capacitive reactance acting to inhibit a phase shift in excess of said 180* phase shift at said output terminal.
Claim 12
Dependent Claim
124 words
An operational amplifier including in combination; a plurality of transistor stages direct current coupled together in cascade and having an input and output terminal, said stages being operative to provide at least 180* phase shift for signals coupled thereto with said phase shift increasing with increasing signal frequency, feedback circuit means connected from said output terminal to said input terminal, supply voltage means coupled to said stages for supplying bias voltages thereto, and diode means direct current coupled from one stage to a previous stage and reverse biased by the bias voltages thereat, said diode means when reverse biased developing a capacitive reactance thereacross, said capacitive reactance acting to inhibit a phase shift in excess of said 180* phase shift at said output 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) | 1976-04-23 | 1976-10-23 | 1977-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-23 | 1980-10-23 | 1981-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-23 | 1984-10-23 | 1985-04-24 | $7700.00 | Window Closed / Lapsed |