Patent ID: 6300836
Filing Date: 2001-10-09
Classification: H03F

Abstract:
An amplifier circuit comprising:a basic amplifier includinga first and a second transistor of opposite type in which the emitter terminal of the first transistor is connected to the input of the second transistor, and in which the collector terminal of the first transistor is connected to the emitter terminal of the second transistor to form a first current summing point, anda current mirror circuit connected to the first and second transistors and to a first supply voltage terminal to provide substantially equal collector currents in each of the first and second transistors; anda constant current source connected between said first current summing point and a second supply voltage terminal to control the DC bias point of the first and second transistors, so as to control, in use, the DC bias point of the amplifier circuit independent of any emitter load of the second transistor.