IC class AB amplifier output stage
AssigneeNational Semiconductor Corporation
InventorMatsuro Koterasawa
Life of this patent
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Abstract
A class AB monolithic silicon IC output stage is shown wherein the main output transistors are NPN structures. The current sourcing transistor is provided with an additional scaled down reference emitter and the two emitters connected to the inputs of an op amp which has its output coupled to drive the current sink transistor. The base of the current source transistor is driven from a high gain driver transistor stage which may also contain a d-c level shifter that permits the inclusion of a complementary current sink transistor that can greatly reduce cross-over distortion while conducting only quiescent current.
Claims9
An integrated output stage circuit having an input and output terminals and first and second power supply terminals connectable to a source of operating power, said circuit comprising:
- a source NPN transistor having its emitter coupled to said output terminal, its collector coupled to said first power supply termial and a base;
- a source reference NPN transistor having its collector and base terminals coupled to like elements in said source NPN transistor and an emitter;
- a sink NPN transistor having its collector coupled to said output terminal, its emitter coupled to said second power supply terminal, and a base;
- an operational amplifier having its non-inverting input coupled to said emitter of said source NPN transistor, its inverting input coupled to said emitter of said source reference transistor and its output coupled to said base of said sink NPN transistor;
- and
- signal drive means coupled to said base of said source NPN transistor.
An integrated output stage circuit having an input and output terminals and first and second power supply terminals connectable to a source of operating power, said circuit comprising:
- a dual emitter NPN transistor having its collector coupled to said first power supply terminal, a base, a source emitter coupled to said output terminal and a reference emitter;
- a sink NPN transistor having its collector coupled to said output terminal, its emitter coupled to said second power supply terminal, and a base;
- an operational amplifier having its non-inverting input coupled to said source emitter, its inverting input coupled to said reference emitter and its output coupled to said base of said sink NPN transistor;
- and
- signal drive means coupled to said base of said dual emitter NPN transistor.
Dependencies are inferred from the claim text.