METHOD OF REMOVING OFFSET VOLTAGE OF OPERATIONAL AMPLIFIER AND OPERATIONAL AMPLIFIER SYSTEM CLEAR OF OFFSET VOLTAGE

摘要

PROBLEM TO BE SOLVED: To provide a method of removing an offset voltage of an operational amplifier which consists of one operational amplifier, one capacitor, and three switches, and also to provide an operational amplifier system clear of an offset voltage. SOLUTION: The operational amplifier system comprises a first switch 10, second switch 12 with a first terminal connected to a first terminal of the first switch 10 and to an input signal Vin, capacitor 17 with a first terminal connected to a second terminal of the first switch 10 and a second terminal connected to a second terminal of the second switch 12, third switch 14 with a first terminal connected to a second terminal of the capacitor 17, and operational amplifier 18 which has a non-inversion input terminal, inversion input terminal, and output terminal, with the non-inversion input terminal connected to a second terminal of the third switch 14 and the non- inversion input terminal connected to a first terminal of the capacitor 17 and the output terminal connected to the non-inversion input terminal. At an automatic return- to-zero phase, the first switch 10 and the third switch 14 are closed and the second switch 12 is opened. At an amplified phase, the first switch 10 and the third switch 14 are opened and the second switch 12 is closed.