Patent ID: 6417733
Filing Date: 2002-07-09
Classification: H03F

Abstract:
A high efficiency, low crossover distortion, current amplifier circuit having an input and output node for amplifying an input signal comprising:a first current source for providing bias current to a sourcing circuit coupled to a first power supply rail; an output driver coupled to the first current source and the output node, the output driver including a sourcing circuit; a first transistor having a collector, base and emitter, the base and collector coupled to the current source; a resistor coupled between the emitter of the first transistor and the output node; and a translinear loop circuit coupled to the input node, the first transistor, and the output driver, the translinear loop circuit comprising, a sinking circuit having a second transistor including a collector, base and emitter, the translinear loop circuit responsive to a sinking current of the sinking circuit and operable to provide a bias current signal proportional to the sinking current, a third transistor having a collector, base and emitter, the collector coupled to the first power supply rail, the base coupled to the input node, a second resistor coupled to the emitter of the third transistor, a fourth transistor having a collector, base and emitter, the collector and base coupled to the second resistor, the emitter coupled to a second power supply rail, a fifth transistor having a collector, base and emitter, the base coupled to the base of the fourth transistor, the emitter coupled to the second power supply rail, the collector coupled to the emitter of the first transistor, a sixth transistor having a collector, base and emitter, the collector coupled to the first power supply rail, the base coupled to the input node, a second current source coupled between the emitter of the sixth transistor and the second power supply rail, the second current source coupled to the sourcing circuit, and wherein the collector of the second transistor of the sinking circuit is coupled to the output node, the base of the second transistor of the sinking circuit is coupled to the second current source, and the emitter of the second transistor of the sinking circuit is coupled to the second power supply rail.