Patent ID: 6369653
Filing Date: 2002-04-09
Classification: H03F

Abstract:
A class AB amplifier biasing circuit for controlling the quiescent state of a pull up output device and a complimentary pull down output device, the biasing circuit comprising:a) a first current source and a first floating resistor configured to supply quiescent current to said pull up output device; b) a second current source and a second floating resistor configured to supply quiescent current to said pull down output device, wherein said first and second floating resistors each comprise a transistor having a gate, drain, and source node; c) a first gate control circuit configured to control the gate voltage of said first floating resistor; and d) a second gate control circuit configured to control the gate voltage of said second floating resistor; wherein at least one of said first and second gate control circuits includes a device replica transistor, the gate of which is connected to a voltage node associated with the gate of one of said pull up device and said pull down output device.