Patent EP0312016A2 successfully refreshed from Google Patents.
EP0312016A2
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Linear differential amplifier
Assignee: Toshiba Corp
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Filing: 1988-10-12
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Granted: —
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Expires: 2008-10-12
Abstract
Abstract A differential amplifier with improved linearity is disclosed. The amplifier includes a circuit comprised of two emitter-coupled pairs (10,20), each pair (10,20) being formed by two transistors (Q₁,Q₂;Q₃ Q₄), with connections between corresponding collectors (11,13;12,14), and constant voltage sources (E₁,E₂) for producing offsets between corresponding bases (1,3;2,4) of the emitter-coupled pairs (10,20). The improved linearity is achieved by obtaining outputs as sums of collector currents with offsets. The emitter areas of the transistors can be of the minimum size available. This feature, when combined with the use of emitter-followers as the constant voltage sources (E₁,E₂), enable the differential amplifier to achieve a high S/N ratio, a good high-frequency characteristic, a high direct current gain, and a high-speed operation capability along with the improved linearity.
Inventors
- 👤 Mikio Koyama
- 👤 Hiroshi Tanimoto
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 22:19
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/32; H03F1/3211
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
264 words
A linear differential amplifier, comprising: a pair of first and second transistors (10) with their emitters coupled to each other; a pair of third and fourth transistors (20) with their emitters coupled to each other, a collector (11) of the first transistor (Q₁) being connected to a collector (13) of the third transistor (Q₃), and a collector (12) of the second transistor (Q₂) being connected to a collector (14) of the fourth transistor (Q₄); a pair of input terminals (17,18), one (17) of which being coupled to the base (1) of the first transistor (Q₁), the other one (18) of which being coupled to the base (4) of the fourth transistor (Q₄); a pair of output terminals (15,16), one (15) of which being connected to the collectors (11,13) of the first and the third transistors (Q₁,Q₃), the other one (16) of which being connected to the collectors (12,14) of the second and the fourth transistors (Q₂,Q₄); constant current source means (7,8) for supplying emitter currents (I e ) to the transistors(Q₁,Q₂,Q₃,Q₄); and load resistor means(5,6) for converting collector currents (I₁,I₂) of the transistors (Q₁,Q₂,Q₃,Q4) into output voltages, characterized by comprising: first voltage source means (E₁) for applying first offset DC voltages between one of the input terminals (17) and a base (3) of the third transistor (Q 3Y ); and second voltage source means (E₂) for applying second offset DC voltages of the same magnitude but in the opposite direction of the first offset DC voltage, between the other one of the input terminals (18) and a base (2) of the second transistor (Q₂).
Claim 2
Dependent Claim
264 words
A linear differential amplifier, comprising: a pair of first and second transistors (10) with their emitters coupled to each other; a pair of third and fourth transistors (20) with their emitters coupled to each other, a collector (11) of the first transistor (Q₁) being connected to a collector (13) of the third transistor (Q₃), and a collector (12) of the second transistor (Q₂) being connected to a collector (14) of the fourth transistor (Q₄); a pair of input terminals (17,18), one (17) of which being coupled to the base (1) of the first transistor (Q₁), the other one (18) of which being coupled to the base (4) of the fourth transistor (Q₄); a pair of output terminals (15,16), one (15) of which being connected to the collectors (11,13) of the first and the third transistors (Q₁,Q₃), the other one (16) of which being connected to the collectors (12,14) of the second and the fourth transistors (Q₂,Q₄); constant current source means (7,8) for supplying emitter currents (I e ) to the transistors(Q₁,Q₂,Q₃,Q₄); and load resistor means(5,6) for converting collector currents (I₁,I₂) of the transistors (Q₁,Q₂,Q₃,Q4) into output voltages, characterized by comprising: first voltage source means (E₁) for applying first offset DC voltages between one of the input terminals (17) and a base (3) of the third transistor (Q 3Y ); and second voltage source means (E₂) for applying second offset DC voltages of the same magnitude but in the opposite direction of the first offset DC voltage, between the other one of the input terminals (18) and a base (2) of the second transistor (Q₂).
Claim 3
Dependent Claim
51 words
The amplifier of claim 1, wherein each voltage source means (E₁;E₂) includes a pair of emitter-followers (21,22;23,24) with each emitter follower including transistors (Q₅,Q₆;Q₇ Q₈) of different emitter areas, and emitter current sources (25a,25b;25c,25d) which supply constant emitter currents (I o ) to all the transistors of the emitter-followers (Q₅,Q₆;Q₇ Q₈).
Claim 4
Dependent Claim
59 words
The amplifier of claim 1, wherein each voltage source means (E₁;E₂) includes a pair of emitter-followers (26,27;28,29) with each emitter follower including transistors (Q₅,Q₉;Q₇,Q₁₀) of the same emitter areas but different collector currents, and emitter current sources (25b,30a;25d,30b) for each transistor of the emitter-followers (Q₅,Q₉;Q₇ Q₁₀)which supply emitter currents (I o ,4I o ) corresponding to the collector currents.
Claim 5
Dependent Claim
48 words
The amplifier of claim 1, wherein each voltage source means (E₁;E₂) includes a pair of emitter-followers with each emitter-follower including transistors of different emitter areas and different collector currents, and emitter current sources for each transistor of the emitter-followers which supply emitter currents corresponding to the collector currents.
Claim 6
Dependent Claim
69 words
The amplifier of claim 1, wherein the first and the fourth transistors (Q₁₁;Q₁₂) have emitter areas different from that of the second and third transistors (Q₂;Q₃), and wherein each voltage means (E₁;E₂) includes a pair of emitter-followers (21,31;23,32) with each emitter-follower including transistors (Q₅,Q₁₃;Q₇,Q₁₄) of different emitter areas, and emitter current sources (25a,25b;25c25d) which supply constant emitter currents (I o ) to all the transistors of the emitter-followers (Q₅,Q₁₃;Q₇,Q₁₄).
Claim 7
Dependent Claim
17 words
The amplifier of claim 1, wherein each transistor (Q₁,Q₂,Q₃,Q4) has a diode (D₁,D₂,D₃,D₄) connected to its emitter.
Claim 8
Dependent Claim
38 words
The amplifier of claim 2, wherein each of constant current source means (7,8) and emitter current sources (25a,25b,25c25d) is comprised of a transistor (Q₁₅,Q₁₆,Q₁₇, Q₁₈, Q₁₉, Q₂₀) with a resistor (33a,33b,35a,35b,35c,35d) connected between its emitter and the ground.
Claim 9
Dependent Claim
33 words
The amplifier of claim 3, wherein each of constant current source means (7,8) and emitter current sources (25b,25d,30a,30b) is comprised of a transistor with a resistor connected between its emitter and the ground.
Claim 10
Dependent Claim
31 words
The amplifier of claim 4, wherein each of constant current source means and emitter current sources is comprised of a transistor with a resistor connected between its emitter and the ground.
Claim 11
Dependent Claim
33 words
The amplifier of claim 5, wherein each of constant current source means (7,8) and emitter current sources (25a,25b,25c,25d) is comprised of a transistor with a resistor connected between its emitter and the ground.
References Cited (Backward Citations)
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