Patent ID: 6292057
Filing Date: 2001-09-18
Classification: H03F

Abstract:
An output stage of an amplifier circuit having an input amplifier stage, a first power supply reference and a second power supply reference, the output stage comprising:an output driver including sourcing circuitry coupled to sinking circuitry, the sourcing circuitry and the sinking circuitry having a common output node, the sourcing circuitry operable to source an output current to an external load, the sinking circuitry operable to sink current from the external load;a sink control circuit coupled to the sinking circuitry and operable to sense the current in the sinking circuitry for providing a sinking current signal proportional to the current in the sinking circuitry;a translinear loop circuit coupled to the sink control circuitry, the translinear loop circuit responsive to the sinking current signal and operable to provide a bias current signal inversely proportional to the sinking current; anda first mirroring circuit coupled to the translinear loop circuit and the sourcing circuitry, the first mirroring circuit operable to mirror the bias current signal from the translinear loop circuit for driving the sourcing circuitry;wherein the sourcing circuit includes a sourcing transistor having a collector coupled to the first reference power supply, a base directly coupled to the first mirroring circuit, and an emitter coupled to the common output node and the sinking circuit includes a sinking transistor having a collector coupled to the emitter of the transistor of the sourcing circuit, an emitter coupled to the second reference power supply and a base.