Audio bridge circuit
AssigneeMotorola, Inc.
InventorWilliam E. Main
Life of this patent
Estimating the term…
Abstract
A circuit responsive to applied audio signals for amplifying the same and providing the amplified signals across differential output terminals. The circuit comprising an audio amplifying section which is responsive to the audio input signals for amplifying the same and a feedback circuit connected across the output terminals for providing a feedback signal to the amplifier section to reduce any direct current offset voltage errors appearing across the output terminals to a minimum value. Additionally, the amplifier section includes circuitry for setting the quiescent voltage bias levels of the output terminals to a predetermined level and for providing common-mode rejection of voltage supply line ripple.
Claims18
Audio bridge circuit having an input terminal, first and second output terminals, comprising:
- amplifier means coupled between the input and first and second output terminals of the audio bridge circuit for amplifying input signals applied to the input terminal and providing the amplified signals across the first and second output terminals, said amplifier means including current mirror circuit means for setting both the first and second output terminals at a predetermined quiescent dc bias potential level the magnitude of which is substantially equal to one-half the magnitude of a first operating potential supplied to the audio bridge circuit;
- feedback circuit means having first and second inputs connected to the first and second output terminals of the audio bridge circuit respectively, said feedback circuit means being responsive to a direct current offset voltage appearing at said first and second inputs thereof for providing a feedback signal to said amplifier means to cause said direct current offset voltage to be severely reduced.
Audio bridge circuit having an input terminal, first and second output terminals, comprising:
- amplifier means coupled between the input and first and second output terminals for amplifying input signals supplied thereto including current mirror circuit means for setting both the first and second output terminals at a predetermined quiescent dc bias potential level;
- first electron control means having first, second and control electrodes, said control electrode being coupled to the input terminal of the audio bridge circuit, said first electrode being coupled to the first output terminal of the audio bridge circuit, said second electrode being coupled with said current mirror circuit means;
- second electron control means having first, second and control electrodes, said control electrode being connected to a terminal at which is provided a ground reference potential, said first electrode being coupled to the second output terminal of the audio bridge circuit, said second electrode being coupled to said current mirror circuit means for setting the quiescent voltage bias levels;
- resistive circuit means coupled between the first and second output terminals of the audio bridge circuit to said first electrodes of said first and second electron control means;
- feedback circuit means having first and second inputs connected to the first and second output terminals of the audio bridge circuit respectively, said feedback circuit means being responsive to a direct current offset voltage appearing at said first and second inputs thereof to provide a feedback signal to severely reduce said offset voltage and including first differential comparator means having first and second inputs and first and second outputs, said first and second inputs being coupled with the first and second output terminals of the audio bridge circuit respectively, second differential comparator means having first and second inputs and first and second outputs, said first and second inputs being coupled respectively to said first and second outputs of said first differential comparator means, said first and second outputs being coupled respectively to said second electrodes of said first and second electron control means.
Dependencies are inferred from the claim text.