Amplifiers – With semiconductor amplifying device – Including differential amplifier
Patent
1982-06-11
1984-06-12
Mullins, James B.
Amplifiers
With semiconductor amplifying device
Including differential amplifier
330260, 330293, H03G 310
Patent
active
044544782
ABSTRACT:
A gain-controlled amplifier comprises input signal amplifying means; first and second bipolar transistor pairs each having a joined emitter connected to each other and driven by an output of the input signal amplifying means, bases of one transistors of said transistor pairs being commonly connected, and bases of the other transistors of said transistor pairs being commonly connected; and addition means for adding a signal representing a difference between collector currents of said the one transistor of the first transistor pair and said the other transistor of the second transistor pair to a signal representing a difference between collector currents of said the other transistor of the first transistor pair and said the one transistor of the second transistor pair, wherein a control voltage is applied between said two common-connected bases; an output of said addition means is negative-fed back to an input side of said input signal amplifying means; and either one of said signals to be added by said addition means is derived as an output of said gain-controlled amplifier. Furthermore the gain-controlled amplifier of the present invention may preferably be provided with a control voltage symmetrical with respect to ground and with a compensating circuit for a difference between transistor characteristics of opposite conductivity types.
REFERENCES:
patent: 3908172 (1975-09-01), Aschermann et al.
Mottola Steven J.
Mullins James B.
Nippon Gakki Seizo Kabushiki Kaisha
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