Patent US3678406A successfully refreshed from Google Patents.
US3678406A
Expired / Lapsed
US
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Variable gain amplifier
Assignee: RCA Licensing Corp
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Filing: 1970-08-26
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Granted: 1972-07-18
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Expires: 1990-08-26
Abstract
Abstract A variable gain direct current coupled amplifier having a fixed DC output level and suitable for fabrication on an integrated circuit chip.
Inventors
- 👤 Jack Avins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 04:53
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/02; H03G3/04; H03G3/10; H03G1/00; H03G1/0005; H03G1/0017
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
356 words
A signal translating amplifier having a variable gain responsive to a control signal comprising: a. first and second transistors each having emitter, base, and collector electrodes, the collector electrode of said first transistor being coupled through first output circuit means to a first terminal adapted for the application of a first source of potential, the collector electrode of said second transistor being coupled through second output circuit means to a second terminal adapted for the application of a second source of potential, the emitter electrodes of said first and second transistors being coupled to a third terminal; b. means coupled to the base electrodes of said first and second transistors for establishing a flow of similar first direct currents through said first and second output circuit means, said first and second output circuit means having a second direct current flowing therethrough; c. input circuit means coupled to the base electrode of said first transistor for applying signals to be translated; d. means coupled to the collector electrode of said second transistor for duplicating said second direct current in said first output circuit means, including a third transistor having emitter, base, and collector electrodes, the collector electrode of said third transistor being coupled to said first output circuit means, the base electrode of said third transistor being coupled to the collector of said second transistor, the emitter electrode of said third transistor being coupled to said third terminal and a diode being coupled from the base to the emitter of said third transistor; e. fourth and fifth transistors having base, emitter and collector electrodes, the collector electrode of said fourth transistor being coupled to the base electrode of said first transistor, the collector electrode of said fifth transistor being coupled to the base electrode of said second transistor, the emitter electrodes of said fourth and fifth transistors being coupled to said third terminal; and f. means for coupling said control signal to the base electrode of said fourth and fifth transistors to vary the gain of said first transistor while maintaining the DC voltage between the collector of said first transistor and said third terminal substantially constant.
Claim 2
Dependent Claim
356 words
A signal translating amplifier having a variable gain responsive to a control signal comprising: a. first and second transistors each having emitter, base, and collector electrodes, the collector electrode of said first transistor being coupled through first output circuit means to a first terminal adapted for the application of a first source of potential, the collector electrode of said second transistor being coupled through second output circuit means to a second terminal adapted for the application of a second source of potential, the emitter electrodes of said first and second transistors being coupled to a third terminal; b. means coupled to the base electrodes of said first and second transistors for establishing a flow of similar first direct currents through said first and second output circuit means, said first and second output circuit means having a second direct current flowing therethrough; c. input circuit means coupled to the base electrode of said first transistor for applying signals to be translated; d. means coupled to the collector electrode of said second transistor for duplicating said second direct current in said first output circuit means, including a third transistor having emitter, base, and collector electrodes, the collector electrode of said third transistor being coupled to said first output circuit means, the base electrode of said third transistor being coupled to the collector of said second transistor, the emitter electrode of said third transistor being coupled to said third terminal and a diode being coupled from the base to the emitter of said third transistor; e. fourth and fifth transistors having base, emitter and collector electrodes, the collector electrode of said fourth transistor being coupled to the base electrode of said first transistor, the collector electrode of said fifth transistor being coupled to the base electrode of said second transistor, the emitter electrodes of said fourth and fifth transistors being coupled to said third terminal; and f. means for coupling said control signal to the base electrode of said fourth and fifth transistors to vary the gain of said first transistor while maintaining the DC voltage between the collector of said first transistor and said third terminal substantially constant.
Claim 3
Dependent Claim
60 words
A variable gain amplifier according to claim 1 wherein said diode comprises a sixth transistor, having emitter, base, and collector electrodes, the collector and base electrodes of said sixth transistor being directly connected together and coupled to the base electrode of said third transistor, the emitter electrode of said sixth transistor being coupled to the emitter of said third transistor.
Claim 4
Dependent Claim
261 words
A variable gain amplifier comprising: first variable gain means having a gain control signal input terminal and an output terminal, at least first and second transistors direct current coupled between said terminals, said first transistor being connected in a common emitter configuration with a collector electrode coupled to said output terminal, said second transistor having collector and emitter electrodes direct current coupled, respectively, to base and emitter electrodes of said first transistor, means for providing direct current collector to base feedback in said second transistor, and means for coupling said base electrode of said second transistor to said gain control signal input terminal, said second transistor being arranged in a common emitter configuration with respect to said gain control signals, second variable gain means coupled to said gain control signal input terminal and to said output terminal, said second variable gain means having at least third and fourth transistors coupled together in a like manner as sAid first and second transistors and further having gain control signal inverting means in cascade relation with said third and fourth transistors between said gain control input and output terminals for maintaining a substantially constant quiescent voltage at said output terminal as gain control signals supplied to said input terminal are varied and means for coupling signals to be amplified to at least one of said base electrodes of said first and third transistors, whereby signals produced at said output terminal are variable in amplitude according to gain control signals applied to said first and second means while said quiescent voltage is maintained substantially constant.
Claim 5
Dependent Claim
261 words
A variable gain amplifier comprising: first variable gain means having a gain control signal input terminal and an output terminal, at least first and second transistors direct current coupled between said terminals, said first transistor being connected in a common emitter configuration with a collector electrode coupled to said output terminal, said second transistor having collector and emitter electrodes direct current coupled, respectively, to base and emitter electrodes of said first transistor, means for providing direct current collector to base feedback in said second transistor, and means for coupling said base electrode of said second transistor to said gain control signal input terminal, said second transistor being arranged in a common emitter configuration with respect to said gain control signals, second variable gain means coupled to said gain control signal input terminal and to said output terminal, said second variable gain means having at least third and fourth transistors coupled together in a like manner as sAid first and second transistors and further having gain control signal inverting means in cascade relation with said third and fourth transistors between said gain control input and output terminals for maintaining a substantially constant quiescent voltage at said output terminal as gain control signals supplied to said input terminal are varied and means for coupling signals to be amplified to at least one of said base electrodes of said first and third transistors, whereby signals produced at said output terminal are variable in amplitude according to gain control signals applied to said first and second means while said quiescent voltage is maintained substantially constant.
Claim 6
Dependent Claim
68 words
A variable gain amplifier according to claim 3 wherein: said means for providing direct current collector to base feedback comprises a resistor, and said gain control signal inverting means comprises a load resistor coupled to the collector of said third transistor and a current duplicator having an input coupled to the junction of said load resistor and said last-named collector and an output coupled to said output terminal.
Claim 7
Dependent Claim
55 words
A variable gain amplifier according to claim 4 wherein: said current duplicator comprises a fifth transistor having emitter, base and collector electrode, said last-named collector being coupled to said output terminal and means having a conduction characteristic proportionally related to that of said fifth transistor connected between said base and emitter of said fifth transistor.
Claim 8
Dependent Claim
42 words
A variable gain amplifier according to claim 5 wherein: said means having a proportionally related conduction characteristic comprises a sixth transistor having direct current coupling between collector and base electrodes and an emitter electrode coupled to the emitter of said fifth transistor.
Claim 9
Dependent Claim
41 words
A variable gain amplifier according to claim 6 wherein: substantially identical gain control signals are supplied to said first and second variable gain means, said first and third transistors are substantially identical and said second and fourth transistors are substantially identical.
Claim 10
Dependent Claim
17 words
A variable gain amplifier according to claim 7 wherein: said fifth and sixth transistors are substantially identical.
References Cited (Backward Citations)
US3512096A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-07-18 | 1976-01-17 | 1976-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-18 | 1980-01-17 | 1980-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-18 | 1984-01-17 | 1984-07-18 | $7700.00 | Window Closed / Lapsed |