Wideband differential amplifier
First Claim
Patent Images
1. A differential amplifier comprising:
- a pair of control devices respectively provided with an output terminal, a control terminal, and a common terminal, anda pair of input devices coupled respectively to said control terminals and receiving input current for providing thereacross the input applied to each said control device, said input devices each having at least input terminals and common terminals, said input devices having logarithmic characteristics substantially matching that of the pair of control devices for producing a linear output at said output terminals,and means coupling together the common terminals of said pairs of devices to a common current connection,wherein said pair of control devices comprises a pair of transistors having their emitter terminals interconnected and wherein said input devices each comprise semiconductor means including a semiconductor junction for receiving input currents and providing thereacross the input applied to the base terminals of said transistors, common terminals of the semiconductor junction means being connected to the emitter terminals of said pair of transistors,wherein said input devices comprise diodes having their cathodes connected to the emitter of said pair of transistors,wherein the emitters of said transistors have a junction area A times the junction areas of said diodes to provide an amplifier having a gain of A.
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Abstract
A wideband differential amplifier comprises a pair of differentially connected control devices, for example transistors, having a pair of semiconductor junction input devices coupled thereto for receiving complementary input currents. The input devices exhibit logarithmic characteristics substantially compensating for nonlinear properties of the pair of differentially connected control devices, whereby a linear rather than a nonlinear amplified current output is produced. Multipliers, cascaded amplifiers, and other useful circuit configurations are provided.
36 Citations
19 Claims
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1. A differential amplifier comprising:
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a pair of control devices respectively provided with an output terminal, a control terminal, and a common terminal, and a pair of input devices coupled respectively to said control terminals and receiving input current for providing thereacross the input applied to each said control device, said input devices each having at least input terminals and common terminals, said input devices having logarithmic characteristics substantially matching that of the pair of control devices for producing a linear output at said output terminals, and means coupling together the common terminals of said pairs of devices to a common current connection, wherein said pair of control devices comprises a pair of transistors having their emitter terminals interconnected and wherein said input devices each comprise semiconductor means including a semiconductor junction for receiving input currents and providing thereacross the input applied to the base terminals of said transistors, common terminals of the semiconductor junction means being connected to the emitter terminals of said pair of transistors, wherein said input devices comprise diodes having their cathodes connected to the emitter of said pair of transistors, wherein the emitters of said transistors have a junction area A times the junction areas of said diodes to provide an amplifier having a gain of A.
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2. A differential amplifier comprising:
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a pair of control devices respectively provided with an output terminal, a control terminal, and a common terminal, and a pair of input devices coupled respectively to said control terminals and receiving input current for providing thereacross the input applied to each said control device, said input devices each having at least input terminals and common terminals, said input devices having logarithmic characteristics substantially matching that of the pair of control devices for producing a linear output at said output terminals, and means coupling together the common terminals of said pairs of devices to a common current connection, wherein said pair of control devices comprises a pair of transistors having their emitter terminals interconnected and wherein said input devices each comprise semiconductor means including a semiconductor junction for receiving input currents and providing thereacross the input applied to the base terminals of said transistors, common terminals of the semiconductor junction means being connected to the emitter terminals of said pair of transistors, wherein said input devices comprise diode-connected transistors having their emitters connected to the emitters of said pair of transistors, wherein the emitters of the pair of transistors have emitter areas A times the emitter areas of said diode-connected transistors to provide an amplifier having a gain of A, the base resistances of said transistors being inversely proportional to said areas.
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3. A cascaded differential amplifier comprising:
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a pair of amplifier input terminals, an amplifier common current terminal, a plurality of circuits each providing a current output linearly proportional to the circuit'"'"'s input current while being characterized by a logarithmic operating characteristic relating voltage in said device to input current, each said circuit including at least one semiconductor device exhibiting a logarithmic voltage in response to current input and a second semiconductor device providing an output current linearly related to said input current, each of said circuits having an input terminal, an output terminal, and a common terminal, means coupling a first pair of said circuits to be driven by said amplifier input terminals, and means coupling further pairs of said circuits with input terminals of circuits of each further pair receiving currents from the common terminals of circuits of the preceding pair, with the last pair having common terminals thereof connected to said amplifier common current terminal. - View Dependent Claims (4, 5)
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6. A wide band differential amplifier, comprising:
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a pair of differentially coupled transistors the emitters of which are coupled together to a suitable source of current, and each having a base terminal and a collector output terminal; and a pair of input devices receiving differential input signal currents and respectively connected to the differentially coupled transistors, said input devices comprising a pair of semiconductor junction devices having junctions similar to those of said differentially coupled transistors, said input devices having logarithmic characteristics substantially matching that of said differentially coupled transistors for producing a linear output at said output terminals. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification