Half-bridge audio amplifier

Claim 2

Means for amplifying an input frequency signal including an output terminal on which the amplified frequency signal appears comprising: a voltage source; a complementary symmetry transistor amplifier including a first transistor and a second transistor of opposite polarity having commonly connected collector electrodes comprising said output terminal, emitter electrodes connected across said voltage source, and first and second control electrode means; transfer amplifier means for applying said input frequency signal to said first and second control electrode means of said first and second transistors; means for supplying quiescent current to said transfer amplifier means whereby said quiescent current flows in said transfer amplifier means and is applied to said first and second control electrode means of said first and second transistors; means for generating a second current equal to said quiescent current and for applying said second current to said first and second control electrode means in a direction to cancel said supplied quiescent current therefrom.

Claim 3

Means for amplifying an input frequency signal as recited in claim 1 wherein said transfer amplifier means comprises: a first amplifier comprising a third transistor having a base electrode connected to receive said input frequency signal, a collector electrode connected to said first control electrode means and an emitter electrode and, a fourth transistor having base and collector electrodes and an emitter electrode connected to said third transistor emitter electrode; a second amplifier comprising a fifth transistor having a base electrode connected to receive said input frequency signal, a collector electrode connected to said second control electrode means and an emitter electrode; and, a sixth transistor having base and collector electrodes and an emitter electrode connected to said fifth transistor emitter electrode; said means for supplying quiescent current being connected to said fourth and sixth transistor collector electrodes; and wherein said means for supplying quiescent current includes voltage means connected across said fourth and sixth transistor base electrodes whereby said quiescent current is caused to flow.

Claim 4

Means for amplifying an input frequency signal as recited in claim 2 wherein said quiescent current is comprised of first and second components, said first component being supplied to said first amplifier and said second current component being supplied to said second amplifier, and wherein said second current is comprised of third and fourth components, said third component being applied to said first control electrode means and said fourth component being applied to said second control electrode means and wherein said means for generating and said means for supplying comprise: a first current inverter for generating said first component and said third component equal to said first component; and, a second current inverter for generating said second component and said fourth component equal to said second component.

Claim 5

Amplifying means comprising: a voltage source having first and second terminals; a complementary symmetry transistoR amplifier including a first transistor having first base, emitter and collector electrodes and a second transistor of opposite polarity having second base, emitter and collector electrodes, said collector electrodes being connected in common, said first emitter electrode being connected to said first terminal and said second emitter electrode being connected to said second terminal, means for applying a signal to be amplified to said complementary symmetry transistor amplifier pair, said means for applying including first and second output terminals, at least said second output terminal being characterized by a high source impedance, said first and second output terminals being connected to said first and second base electrodes of said first and second transistors respectively; means for generating a quiescent current in said applying means; means responsive to said quiescent current for generating an equal current and for communicating said equal current to said first and second output terminals so as to cancel said generated quiescent current therefrom.

Claim 6

Amplifying means comprising: a voltage source having first and second terminals; a complementary symmetry transistoR amplifier including a first transistor having first base, emitter and collector electrodes and a second transistor of opposite polarity having second base, emitter and collector electrodes, said collector electrodes being connected in common, said first emitter electrode being connected to said first terminal and said second emitter electrode being connected to said second terminal, means for applying a signal to be amplified to said complementary symmetry transistor amplifier pair, said means for applying including first and second output terminals, at least said second output terminal being characterized by a high source impedance, said first and second output terminals being connected to said first and second base electrodes of said first and second transistors respectively; means for generating a quiescent current in said applying means; means responsive to said quiescent current for generating an equal current and for communicating said equal current to said first and second output terminals so as to cancel said generated quiescent current therefrom.

Claim 7

Amplifying means as recited in claim 4 wherein said means for applying comprises a class B transfer amplifier means including an input terminal for receiving said signal to be amplified and said first and second output terminals.

Claim 8

Amplifying means as recited in claim 5 wherein said transfer amplifier means comprises: a first differential transistor amplifier comprising a third transistor having a base electrode connected to said input terminal and a differentially connected fourth transistor having a base electrode, said first differential amplifier including said first output terminal; a second differential transistor amplifier comprising a fifth transistor having a base electrode connected to said input terminal and a differentially connected sixth transistor having a base electrode; said second differential amplifier including said second output terminal; and wherein said means for generating a quiescent current comprises: a source of quiescent current for said first and second differential amplifiers; and, a source of forward bias connected across said fourth and sixth transistor base electrodes whereby said quiescent current is biased to flow in said first and second differential amplifiers, said quiescent current thereby appearing at said first and second output terminals.

Claim 9

Amplifying means as recited in claim 6 wherein said fifth transistor includes a collector electrode comprising said second output terminal.

Claim 10

Amplifying means as recited in claim 5 wherein said transfer amplifier comprises: a first differential amplifier comprising a third transistor having a base electrode connected to receive said signal and a collector electrode comprising said first output terminal, and a differentially connected fourth transistor having a base electrode; a second differential amplifier comprising a fifth transistor having a base electrode connected to receive said signal and a collector electrode comprising said second output terminal, and a differentially connected sixth transistor having a base electrode; and wherein said means for generating a quiescent current includes a source of voltage difference connected across said fourth and sixth transistor base electrodes.

Claim 11

Amplifying means as recited in claim 8 wherein said fourth and sixth transistors have collector electrodes and wherein such quiescent current includes first and second components and said equal current includes third and fourth components and wherein said means for generating a quiescent current additionally includes: a source of said first component for said first differential amplifier connected to said fourth collector electrode; a source of said second component for said second differential amplifier connected to said sixth collector electrode, said voltage difference causing said first and second components to flow in said first and second differential amplifiers and to thereby apPear at said first and second output terminals respectively; and wherein said means for generating an equal current comprises: means for generating said third component essentially equal to said first component; and, means for generating said fourth component essentially equal to said second component, said third and fourth components comprising said equal current and being applied respectively to said first and second output terminals to cancel the first and second components thereat.