Patent ID: 7498880
Filing Date: 2009-03-03
Classification: H03F

Abstract:
1. An amplifier system comprising: a first amplifier device coupled to receive an input signal and provide a first output signal; and a first rail selector coupled to the first amplifier device, for coupling the first amplifier device to a first power rail and a second power rail in response to the output signal being lower than a first threshold, to couple the first amplifier device to a third power rail and the first power rail in response to the input signal being higher than the first threshold and lower than a second threshold, and to couple the first amplifier device to a fourth power rail and the first power rail in response to the input signal being higher than the second threshold; a second amplifier device coupled to receive an input signal and provide a second output signal; and a second rail selector coupled to the second amplifier device, for coupling the second amplifier device to a fifth power rail and a sixth power rail in response to the output signal being lower than a third threshold, to couple the second amplifier device to a seventh power rail and the fifth power rail in response to the input signal being higher than the third threshold and lower than a fourth threshold, and to couple the second amplifier device to an eighth power rail and the fifth power rail in response to the input signal being higher than the fourth threshold; wherein the first rail selector comprises: wherein, the second intermediate result signal selects the fourth and first power rails for the first amplifier device and the sixth and fifth power rails for the second amplifier device, the third intermediate result signal selects the third and first power rails for the first amplifier device and the sixth and fifth power rails for the second amplifier device, the fifth intermediate result signal selects the second and first power rails for the first amplifier device and the seventh and fifth power rails for the second amplifier device, the sixth intermediate result signal selects the second and first power rails for the first amplifier device and the eighth and fifth power rails for the second amplifier device, and the seventh result signal selects the second and first power rails for the first amplifier device and the sixth and fifth power rails for the second amplifier device.