Patent ID: 7411455
Filing Date: 2008-08-12
Classification: H03F

Abstract:
1. A high current output buffer comprising: a first bipolar transistor with its emitter producing the high output current; a second bipolar transistor having the same polarity as the first, the emitter of the second transistor connected to the collector of the first transistor, and the collector of the second transistor connected to a first voltage source; the base of the first transistor coupled to the collector of a third transistor of the opposite polarity with respect to the first and second transistors; the emitter of the third transistor connected to a first resistor whose distal end is coupled to the first voltage source; the emitter of the third transistor also coupled to the emitter of a fourth transistor of common polarity with the third transistor; the collector of the fourth transistor coupled to its base and to a first current source; the base of the second transistor coupled to a resistor whose distal end is coupled to the first voltage source; the base of the second transistor also coupled to the emitter of a fifth transistor of common polarity to the third and fourth transistors; the collector of the fifth transistor coupled to a second current source; the bases of the fourth and the fifth transistors are coupled together; and the base of the third transistor coupled to the collector of the fifth transistor, wherein the fourth and fifth transistors form a current mirror, and wherein the third, fourth and fifth transistors form a negative feedback loop, and where any incremental base drive for the first transistor to support an incremental current at the emitter of the first transistor is supplied from the collector of the third transistor.