Patent ID: 6531920
Filing Date: 2003-03-11
Classification: H03F

Abstract:
A differential amplifier circuit comprising:a first and second input terminals, a first and second operational amplifiers having negative inputs connected to each of said first and second input terminals respectively, a first and second transistors having bases connected to each output of said first and second operational amplifiers respectively, a first and second constant current sources connected between each emitter of said first and second transistors and a ground terminal respectively, a third and fourth constant current sources connected between each collector of said first and second transistors and a power supply terminal respectively, a first resistor connected between the collectors of said first and second transistors, and a pair of transistors having emitters connected to each emitter of said first and second transistors and having bases commonly connected to each other, wherein the collectors of said first and second transistors are connected to the positive inputs of said first and second operational amplifiers respectively, the commonly-connected bases of said pair of transistors are connected to input terminals for inputting a predetermined signal, and the collectors of said pair of transistors form a set of output terminals and output a set of output currents from said set of output terminals according to an input voltage applied between said first and second input terminals.