Patent ID: 6121839
Filing Date: 2000-09-19
Classification: H03F

Abstract:
A class AB CMOS output stage for an operational amplifier having a rail-to-rail output voltage swing, the output stage comprising:a pair of complementary output transistors;a pair of differential signal lines for providing differential signal currents being in opposing phase to each other;a pair of complementary control transistors connected in opposing phase to each other between driving nodes of said pair of complementary output transistors, a gate of a respective transistor of said pair of complementary control transistors connected to a respective differential signal line of said pair of differential signal lines; andbiasing means for biasing said pair of complementary control transistors, said biasing means comprisinga pair of first and second diodes connected in series between a respective supply line and a respective differential signal line of the pair of differential signal lines, anda first transistor connected to the first diode of a respective pair of diodes forming a current mirror for mirroring a differential signal current for the respective transistor of said pair of complementary control transistors, and to a terminal of the second diode of said pair of diodes.