Patent attributes
To reduce the apparent effect of offset voltage by making the offset voltage spatially scattered. An operational amplifier 1 includes: a first differential pair having N-channel MOS transistors MN1 and MN2; a second differential pair having P-channel MOS transistors MP1 and MP2; an output stage having output transistors NP3 and MN3; first and second active loads 11 and 12 having a switch, adapted to convert differential outputs from the first and second differential pairs to a single output, respectively; first and second bias circuits 13 and 14 having a switch, adapted to select one of two outputs of each of the first and second active loads 11 and 12 having the switch and to determine idling current of the MP3 and MN3, respectively; first and second switches SW1 and SW2 adapted to respectively connect an output terminal and an input terminal to one of the gates of each of the first and second differential pairs; and a terminal 17 adapted to receive an offset cancellation signal for controlling switching functions and the switches in linkage with each other.
