US4456887A
Expired / Lapsed
US
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Differential amplifier
Assignee: Pioneer Corp
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Filing: 1981-09-23
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Granted: 1984-06-26
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Expires: 2001-09-23
Abstract
Abstract Current mirror circuits are added to a differential amplifier and the amplifier differential outputs are taken from one or both of the current paths in the current mirror circuit so that the relationship between input and output signals will be independent of the base-emitter voltages of the differential transistors.
Inventors
- 👤 Akio Tokumo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:15
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/45; H03F3/45071; H03F3/45076; H03F3/4508; H03F3/45085; H03F1/00; H03F1/32; H03F1/3211; H03F3/45098; H03F2203/00; H03F2203/45; H03F2203/45496; H03F2203/45511; H03F2203/45612; H03F2203/45658; H03F2203/45702
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
128 words
A differential amplifier, comprising: a first transistor having a base and having an output terminal for providing an output signal; a second transistor having a base and having an output terminal for providing an output signal; means for applying a differential input to the bases of said first and second transistors; third and fourth transistors each having a base, said first and second transistor outputs being differentially applied across said third and fourth transistor bases; means for supplying currents in a predetermined ratio to said first and third transistors and for supplying currents in a predetermined ratio to said second and fourth transistors; and means for providing a differential amplifier output in accordance with variations of current flow through at least one of said third and fourth transistors.
Claim 2
Dependent Claim
128 words
A differential amplifier, comprising: a first transistor having a base and having an output terminal for providing an output signal; a second transistor having a base and having an output terminal for providing an output signal; means for applying a differential input to the bases of said first and second transistors; third and fourth transistors each having a base, said first and second transistor outputs being differentially applied across said third and fourth transistor bases; means for supplying currents in a predetermined ratio to said first and third transistors and for supplying currents in a predetermined ratio to said second and fourth transistors; and means for providing a differential amplifier output in accordance with variations of current flow through at least one of said third and fourth transistors.
Claim 3
Dependent Claim
48 words
A differential amplifier as defined in claim 1, wherein said first (Q 1 ) and second (Q 2 ) transistors are of one conductivity type and said third (Q 3 ) and fourth (Q 4 ) transistors are of a second conductivity type opposite said first conductivity type.
Claim 4
Dependent Claim
96 words
A differential amplifier as defined in claim 2, wherein said means for providing currents to said first through fourth transistors comprises a first current mirror circuit having a first current path coupled in series with the emitter-collector path of said first transistor and a second current path coupled in series with the emitter-collector path of said third transistor; and a second current mirror circuit having a third current path connected in series with the emitter-collector path of said second transistor and a fourth current path coupled in series with the emitter-collector path of said fourth transistor.
Claim 5
Dependent Claim
51 words
A differential amplifier as defined in claim 3, wherein said means for supplying currents to said first through fourth transistors further comprises a single constant current source coupled through a first resistor (R 3 ) to said third transistor and through a second resistor (R 4 ) to said fourth transistor.
Claim 6
Dependent Claim
69 words
A differential amplifier as defined in claim 3, wherein said means for supplying currents to said first through fourth transistors further comprises a first constant current source (I O1 ) for providing a constant current to said third transistor; a second constant current source (I O1 ) for providing a constant current to said fourth transistor; and a resistor (R E ) coupled between said third and fourth transistors.
Claim 7
Dependent Claim
56 words
A differential amplifier as defined in either claim 1 or 2, wherein each of said first and second transistors is connected in an emitter follower configuration, each having an emitter follower output, and wherein the emitter follower outputs of said first and second transistors are applied to the bases of said third and fourth transistors, respectively.
Claim 8
Dependent Claim
34 words
A differential amplifier as defined in claim 1, wherein said first (Q 11 ), second (Q 12 ), third (Q 14 ) and fourth (Q 13 ) transistors are of the same conductivity type.
Claim 9
Dependent Claim
55 words
A differential amplifier as defined in either claim 1 or 7, wherein each of said first and second transistors is connected in an emitter follower configuration having an emitter follower output, and wherein the emitter follower outputs of said first and second transistors are applied to the bases of said fourth and third transistors, respectively.
Claim 10
Dependent Claim
88 words
A differential amplifier as defined in claim 7, wherein said means for supplying currents to said first through fourth transistors comprises a fifth transistor (Q 15 , Q 19 ) of said one conductivity type and having its emitter-collector path coupled in series with the emitter-collector path of said first transistor (Q 11 ), and a sixth transistor (Q 17 , Q 20 ) of said one conductivity type and having its emitter-collector path coupled in series with the emitter-collector path of said second transistor (Q 12 ).
Claim 11
Dependent Claim
41 words
A differential amplifier as defined in claim 9, wherein the bases of said fifth (Q 19 ) and sixth (Q 20 ) transistors are coupled to the bases of said third (Q 14 ) and fourth (Q 13 ) transistors, respectively.
Claim 12
Dependent Claim
65 words
A differential amplifier as defined in claim 10, wherein said means for supplying currents to said first through fourth transistors further comprises: a source of constant current; a respective resistor coupled between said source of constant current and each of said third through sixth transistors; output resistors (R 11 , R 12 ) coupled to output terminals of each of said third and fourth transistors.
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) | 1987-06-26 | 1987-12-26 | 1988-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-06-26 | 1991-12-26 | 1992-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-06-26 | 1995-12-26 | 1996-06-26 | $7700.00 | Window Closed / Lapsed |