Patent ID: 8754881

Claim:
An operational amplifier comprising: at least one differential input part for generating a voltage signal corresponding to an electric potential difference between a positive-phase input signal and a negative-phase input signal by using a differential pair configured from a pair of transistors; an output part for generating and outputting an output signal of a logic level corresponding to the voltage signal generated by the differential input part; at least one auxiliary current generator for detecting a sudden change in the positive-phase input signal or the negative-phase input signal and generating an auxiliary current; and a drive current generator for adding together a predetermined reference current and the auxiliary current and generating a drive current of the differential input part, wherein the auxiliary current generator comprises: a differentiating circuit for receiving an input of a voltage that appears in a common connection end of the differential pair, and generating a differential waveform signal thereof; and a switch for controlling generation or non-generation of the auxiliary current in accordance with the differential waveform signal.