PURPOSE: To cancel the offset voltage of an operational amplifier without using an operational amplifier having a large through-rate by adding a delay feedback circuit in addition to a feedback circuit.

CONSTITUTION: The delay feedback circuit 4 charges an output with a clock pulse of an operational amplifier 1, applies the charged output at the next inverted clock pulse to an inverting input terminal 11 and forms a new feedback path. Then the offset voltage is charged to the capacitor of the feedback circuit 3 and the input circuit 2 at inverted phase clock pulse. This is canceled with the offset voltage at the terminal 11 at the next clock pulse . As a result, an output voltage not including the offset voltage is obtained from an output terminal 13 of the operational amplifier 1. Thus, it is not required to use an operational amplifier with a large through-rate.