Bipolar rail-to-rail output stage
AssigneeTexas Instruments Incorporated
InventorSergey Alenin
Life of this patent
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Abstract
A bipolar rail-to-rail class-AB output stage that provides improved AC performance in low voltage applications. The bipolar output stage includes an input buffer stage, first and second complementary common emitter stages, and first and second control circuits biased and configured to assure class-AB operation of the first and second common emitter stages, respectively. The input of the bipolar output stage is applied to the input buffer stage, and the output of the bipolar output stage is provided by the second common emitter stage. The combination of the first common emitter stage and the first AB-control circuit operates as a current booster stage for the second common emitter stage, thereby obviating the need for a large power supply.
Claims15
A circuit, comprising:
- an input node and an output node;
- first and second supply nodes;
- an input stage including a first transistor coupled between the first and second supply nodes, the first transistor having a base connected to the input node;
- a current booster stage including a first complementary common emitter stage and a first AB-control circuit operatively coupled to the first common emitter stage, the first common emitter stage and the first AB-control circuit being coupled between the first and second supply nodes, respectively;
- and
- an output stage including a second complementary common emitter stage and a second AB-control circuit operatively coupled to the second common emitter stage, the second common emitter stage and the second AB-control circuit being coupled between the first and second supply nodes, respectively, the second common emitter stage including second and third transistors having respective bases and collectors, the collectors of the second and third transistors being connected to the output node,
- wherein the first common emitter stage includes fourth and fifth transistors having respective collectors connected to the bases of the second and third transistors, respectively, and
- wherein the first transistor has an emitter connected to the base of at least one of the second and third transistors.
Dependencies are inferred from the claim text.