US3719833A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Technique for compensating for input bias currents of transistors
Assignee: Motorola Solutions Inc
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Filing: 1970-10-12
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Granted: 1973-03-06
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Expires: 1990-10-12
Abstract
Abstract Input bias currents, or base currents, of transistors of one conductivity type may be compensated for by connecting the base thereof to the base of a transistor of the opposite conductivity type. The betas of the two transistors should be equal and the other transistor characteristics of the transistors should be matched. The transistors should be placed close together so as to be subject to the same environmental conditions. The transistors may, conveniently, be on the same chip as in an integrated circuit, and the principal transistors, as well as compensating transistors may be connected as Darlington pairs.
Inventors
- 👤 M Free
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 07:17
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/45; H03F3/45071; H03F3/45479; H03F1/00; H03F1/56
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
193 words
A circuit for compensating for undesired environmentally induced changes of the base currents as compared with the signal base currents of a first pair of transistors of one conductivity type connected as a differential pair and having their emitters and collectors adapted to be connected across a source of supply, having their bases adapted to be connected to a signal source, having certain transistor characteristics, and being adapted to be subjected to the environment susceptible of inducing such changes comprising a second pair of transistors of the opposite conductivity type having their emitters and collectors adapted to be connected across said source of supply in opposite relation to said first transistors and being adapted to be subjected to the same environment as said first pair of transistors, said second pair of transistors having essentially matched characteristics to said first pair of transistors, the base of one of said second pair of transistors being connected to the base of one of said first pair of transistors, and the base of the other one of said second pair of transistors being connected to the bases of the other one of said first pair Of transistors.
Claim 2
Dependent Claim
193 words
A circuit for compensating for undesired environmentally induced changes of the base currents as compared with the signal base currents of a first pair of transistors of one conductivity type connected as a differential pair and having their emitters and collectors adapted to be connected across a source of supply, having their bases adapted to be connected to a signal source, having certain transistor characteristics, and being adapted to be subjected to the environment susceptible of inducing such changes comprising a second pair of transistors of the opposite conductivity type having their emitters and collectors adapted to be connected across said source of supply in opposite relation to said first transistors and being adapted to be subjected to the same environment as said first pair of transistors, said second pair of transistors having essentially matched characteristics to said first pair of transistors, the base of one of said second pair of transistors being connected to the base of one of said first pair of transistors, and the base of the other one of said second pair of transistors being connected to the bases of the other one of said first pair Of transistors.
Claim 3
Dependent Claim
193 words
A circuit for compensating for undesired environmentally induced changes of the base currents as compared with the signal base currents of a first pair of transistors of one conductivity type connected as a differential pair and having their emitters and collectors adapted to be connected across a source of supply, having their bases adapted to be connected to a signal source, having certain transistor characteristics, and being adapted to be subjected to the environment susceptible of inducing such changes comprising a second pair of transistors of the opposite conductivity type having their emitters and collectors adapted to be connected across said source of supply in opposite relation to said first transistors and being adapted to be subjected to the same environment as said first pair of transistors, said second pair of transistors having essentially matched characteristics to said first pair of transistors, the base of one of said second pair of transistors being connected to the base of one of said first pair of transistors, and the base of the other one of said second pair of transistors being connected to the bases of the other one of said first pair Of transistors.
Claim 4
Dependent Claim
193 words
A circuit for compensating for undesired environmentally induced changes of the base currents as compared with the signal base currents of a first pair of transistors of one conductivity type connected as a differential pair and having their emitters and collectors adapted to be connected across a source of supply, having their bases adapted to be connected to a signal source, having certain transistor characteristics, and being adapted to be subjected to the environment susceptible of inducing such changes comprising a second pair of transistors of the opposite conductivity type having their emitters and collectors adapted to be connected across said source of supply in opposite relation to said first transistors and being adapted to be subjected to the same environment as said first pair of transistors, said second pair of transistors having essentially matched characteristics to said first pair of transistors, the base of one of said second pair of transistors being connected to the base of one of said first pair of transistors, and the base of the other one of said second pair of transistors being connected to the bases of the other one of said first pair Of transistors.
Claim 5
Dependent Claim
379 words
A circuit for compensating for undesired environmentally induced changes of the base current as compared with the signal base current of a different amplifier including a first pair of Darlington connected transistors of one conductivity type and a second pair of Darlington connected transistors of the same conductivity type, the emitters of the second stages of said first and said second Darlington pairs being connected together and to one side of a source of supply, the collectors of the first and second stages of said first Darlington pair being connected together, the collectors of the first and second stages of said second Darlington pair being connected together, balancing circuit means being connected between the connected collector of said first and said second Darlington pairs and the other side of said source of supply, the bases of the first stages of said first and second Darlington pairs being adapted to be connected differentially to a signal source, each of the transistors of said first and second Darlington pairs having certain transistor characteristics, all being adapted to be subjected to the environment susceptible of inducing such changes comprising a third pair of Darlington connected transistors of opposite conductivity type to said first pair and having its emitter circuits and its collector circuits adapted to be connected across said source of supply in opposite relation to said first Darlington pair, the base of the first stage of said third Darlington pair being connected to the base of the first stage of said first Darlington pair and to one input of said differential source, a fourth pair of Darlington connected transistors of opposite conductivity type to said second pair and having its emitter circuits and its collector circuits adapted to be connected across said source of supply in opposite relation to said second Darlington pair, the base of the first stage of said fourth Darlington pair being connected to the base of the first stage of said second Darlington pair and to the other input of said differential source, the transistors of said first, second, third and fourth Darlington pairs being adapted to be subjected to the same environment, the transistors of said third and fourth Darlington pairs having essentially matched characteristics to the transistors of said first and second Darlington pairs, respectively.
Claim 6
Dependent Claim
379 words
A circuit for compensating for undesired environmentally induced changes of the base current as compared with the signal base current of a different amplifier including a first pair of Darlington connected transistors of one conductivity type and a second pair of Darlington connected transistors of the same conductivity type, the emitters of the second stages of said first and said second Darlington pairs being connected together and to one side of a source of supply, the collectors of the first and second stages of said first Darlington pair being connected together, the collectors of the first and second stages of said second Darlington pair being connected together, balancing circuit means being connected between the connected collector of said first and said second Darlington pairs and the other side of said source of supply, the bases of the first stages of said first and second Darlington pairs being adapted to be connected differentially to a signal source, each of the transistors of said first and second Darlington pairs having certain transistor characteristics, all being adapted to be subjected to the environment susceptible of inducing such changes comprising a third pair of Darlington connected transistors of opposite conductivity type to said first pair and having its emitter circuits and its collector circuits adapted to be connected across said source of supply in opposite relation to said first Darlington pair, the base of the first stage of said third Darlington pair being connected to the base of the first stage of said first Darlington pair and to one input of said differential source, a fourth pair of Darlington connected transistors of opposite conductivity type to said second pair and having its emitter circuits and its collector circuits adapted to be connected across said source of supply in opposite relation to said second Darlington pair, the base of the first stage of said fourth Darlington pair being connected to the base of the first stage of said second Darlington pair and to the other input of said differential source, the transistors of said first, second, third and fourth Darlington pairs being adapted to be subjected to the same environment, the transistors of said third and fourth Darlington pairs having essentially matched characteristics to the transistors of said first and second Darlington pairs, respectively.
Claim 7
Dependent Claim
25 words
The invention according to claim 1 wherein the connected emitter circuits of said first and second Darlington pairs includes a transistor constant current source means.
Claim 8
Dependent Claim
38 words
The invention according to claim 3 wherein the emitter collector circuits of said third and fourth Darlington pairs include transistor components for balancing input offset current essentially to zero and to balance input bias currents essentially to zero.
Claim 9
Dependent Claim
29 words
The invention according to claim 3 wherein the emitter collector circuits of said first and second Darlington pairs include transistor components for adjusting input offset voltage essentially to zero.
Claim 10
Dependent Claim
61 words
The invention according to claim 3 wherein the emitter collector circuits of said third and fourth Darlington pairs include transistor components for balancing input currents essentially to zero and to balance input bias currents essentially to zero, and wherein the emitter collector circuits of said first and second Darlington pairs include transistor components for adjusting input offset voltage essentially to zero.
Claim 11
Dependent Claim
24 words
The invention according to claim 2 wherein the transistors of said first, second, third and fourth Darlington pairs are formed on the same chip.
Claim 12
Dependent Claim
36 words
The invention according to claim 2 wherein the transistors of said first and second Darlington pairs are of the PNP type and the transistors of the second and fourth Darlington pairs are of the NPN type.
Claim 13
Dependent Claim
15 words
The invention according to claim 6 wherein the transistors are mounted on the same chip.
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) | 1976-03-05 | 1976-09-04 | 1977-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-05 | 1980-09-04 | 1981-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-05 | 1984-09-04 | 1985-03-06 | $7700.00 | Window Closed / Lapsed |