Patent ID: 6384684
Filing Date: 2002-05-07
Classification: H03F

Abstract:
A class AB amplifier having an output stage comprising complementary common source (or emitter) transistors connected between the power supply rails, first means for setting the minimum (or quiescent) current of the output stage under zero signal conditions, said means comprising a bias resistor through which a bias current is passed and which is connected between the gate (or base) electrodes of the transistors, second means for determining the bias current through the bias resistor, said second means comprising reference current generating means, means for passing the reference current through first and second complementary reference transistors, means for monitoring the gate (or base) potentials of the first and second reference transistors, and means for applying the gate (or base) potentials to opposite ends of a reference resistor, and third means for sensing the current through the reference resistor and applying a current dependent thereon to the bias resistor.