Transistor circuit for the driver stage of a class b amplifier

Claim 2

An audio frequency amplifier circuit comprising an input differential amplifier, two drive circuits connected to said input amplifier to be driven thereby, and to act in push-pull, each driver circuit comprising a driver differential amplifier, two current amplifiers connected respectively to the outputs of said driver differential amplifiers, a push-pull output circuit connected in a push-pull arrangement to said two current amplifiers, a bias setting circuit, said driver differential amplifiers each including a pair of transistors of the same impurity arrangement, including a base, a collector and an emitter, the bases of one of said pair of transistors connected to said bias setting circuit and receiving a first constant voltage, the bases of the other one of said pair of transistors connected to said bias setting circuit.

Claim 3

An audio frequency amplifier according to claim 1 in which the transistors of said driver circuits are pnp transistors, two pair of resistors, respectively connected between the emitters of each of said pairs of transistors and a source of positive d.c. potential connected, respectively to the junction point between said pairs of resistors.

Claim 4

An audio frequency amplifier according to claim 1 in which the transistors of each of said driver circuits are pnp transistors, each having a base, a collector and an emitter, a source of positive d.c. potential, each driver having a pair of resistors serially connected between said emitters of that driver, and a third resistor for each driver connected between the emitters thereof and said d.c. potential.

Claim 5

An audio frequency amplifier according to claim 1 including a d.c. source, said two current amplifiers each include a transistor having a base, a collector and an emitter, the collectors of which are connected to said d.c. source and the bases thereof being connected to outputs of its associated driver, and the emitters thereof being connected to said push-pull output circuit, two constant current circuits, one for each of said output amplifiers, each constant current circuit including an npn transistor having a base, a collector and an emitter, and another voltage source, the collector of each of said last mentioned transistors being connected to the emitter of its associated current amplifier; the emitter thereof being grounded, and the base thereof being connected through the positive side of said another voltage source to ground.

Claim 6

A transistor circuit comprising a first driver circuit having first and second pnp transistors each having a base, a collector and an emitter, a second driver circuit having a third and fourth pnp transistor each having a base, a collector and an emitter, a source of positive d.c. potential, the emitters of said first and second transistors being connected together and to said d.c. source, the emitters of said third and fourth transistors being connected together and to said d.c. source, and a.c. input signal source connected between an input point and ground, a differential input amplifier having fifth and sixth npn transistors each having a collector, a base and an emitter, a constant current source, the base of said fifth transistor being connected to one side of said input signal source, the emitter of said fifth and sixth transistors being connected together and through said constant current source to ground, a pair of resistors connected between the collectors of said fifth and sixth transistors, said collectors being connected to said d.c. source, the collector of said fifth transistor being connected to the base of said first transistor, the collector of said sixth transistor being connected to the base of said third transistor, the collectors of said second and fOurth transistors being grounded, a bias setting circuit, said bias setting circuit supplying the same bias to the biases of said second and fourth transistors, and a push-pull output circuit connected to the collectors of said first and third transistors.

Claim 7

A transistor circuit comprising a first driver circuit having first and second pnp transistors each having a base, a collector and an emitter, a second driver circuit having a third and fourth pnp transistor each having a base, a collector and an emitter, a source of positive d.c. potential, the emitters of said first and second transistors being connected together and to said d.c. source, the emitters of said third and fourth transistors being connected together and to said d.c. source, and a.c. input signal source connected between an input point and ground, a differential input amplifier having fifth and sixth npn transistors each having a collector, a base and an emitter, a constant current source, the base of said fifth transistor being connected to one side of said input signal source, the emitter of said fifth and sixth transistors being connected together and through said constant current source to ground, a pair of resistors connected between the collectors of said fifth and sixth transistors, said collectors being connected to said d.c. source, the collector of said fifth transistor being connected to the base of said first transistor, the collector of said sixth transistor being connected to the base of said third transistor, the collectors of said second and fOurth transistors being grounded, a bias setting circuit, said bias setting circuit supplying the same bias to the biases of said second and fourth transistors, and a push-pull output circuit connected to the collectors of said first and third transistors.