Patent ID: 7057461
Filing Date: 2006-06-06
Classification: H03F

Abstract:
1. A power amplifier comprising: first and second power transistor stages receiving first and second collector supply voltages, respectively, the first power transistor stage comprising a first RF transistor operating in response to the first collector supply voltage applied to a collector thereof and including a base biased by a first bias voltage, the second power transistor stage comprising a second RF transistor operating in response to the second collector supply voltage applied to a collector thereof and including a base biased by a second bias voltage; and a first stage bias circuit including first and second bias transistors and a second bias circuit including third and fourth bias transistors for providing the respective first and second bias voltages, collectors of the second and fourth bias transistors being biased by a third supply voltage and collectors of the first and third bias transistors operating in response to a fourth supply voltage.