US 4,384,261 AGranted

Class A complementary single-ended push-pull amplifier

AssigneeNippon Gakki Seizo Kabushiki Kaisha

InventorKenji Yokoyama

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Abstract

In a complementary single-ended push-pull amplifier in which emitters of first and second complementary bipolar output transistors are connected through first and second emitter resistors to a load such as a loudspeaker, third and fourth complementary bipolar transistors are connected in series between the bases of the first and second bipolar transistors having their emitters connected to a bias voltage source for operating the first and second output transistors in the Class A mode. The bases of third and fourth transistors are respectively connected to the emitters of the first and second transistors, whereby a negative feedback is provided from the emitters of the first and second transistors to the bases thereof. With this arrangement, the sum of the collector currents of the first and second transistors is kept substantially constant and hence distortion of an output current (difference between the collector currents of the output transistors) fed to the load at large signal levels can be improved.

Claims7

Dependent claims

A complementary single-ended push-pull amplifier comprising:

first and second complementary bipolar transistor means;
first and second emitter resistors connected in series between emitters of said first and second complementary bipolar transistor means, a connection point between said emitter resistors being adapted for connection to a load;
third and fourth complementary bipolar transistors connected in series between bases of said first and second transistor means and having their bases connected to the emitters of said first and second transistors, respectively;
a constant voltage circuit connected between the emitters of said third and fourth transistors to operate said first and second transistor means in the Class A mode;
said third and fourth transistors comparing a voltage across said first and second emitter resistors with a voltage of said constant voltage circuit;
and
collector currents of said third and fourth transistors controlling base biases of said first and second transistor means, to thereby operate said first and second transistor means so that a sum of collector currents of said first and second transistor means is kept substantially constant.

4 more elements

Dependencies are inferred from the claim text.