Patent ID: 6262628
Filing Date: 2001-07-17
Classification: H03F

Abstract:
A differential amplifier circuit for processing a signal including an AC voltage signal superimposed on a DC voltage, said amplifier comprising:a first differential amplifier having first and second input terminals and a second differential amplifier having first and second input terminals, the first input terminal of said first differential amplifier being connected to a first terminal of a signal source and the first input terminal of said second differential amplifier being connected to a second terminal of the signal source; anda third differential amplifier having first and second input terminals to which an output terminal of said first differential amplifier and an output terminal of said second differential amplifier are respectively connected, wherein the second input terminal of said first differential amplifier and the second input terminal of said second differential amplifier are connected so that currents having values almost equal to mean values of currents flowing to the respective first input terminals of said first and second differential amplifiers flow at the second input terminals of the first and second differential amplifiers.