PURPOSE: To discriminate a minute potential difference in high speed by providing a feedback circuit in a comparator circuit.

CONSTITUTION: It is when a difference ΔE between voltages E1 and E2 applied to terminals 28 and 29 is small that the response in high speed is a problem, and the change in the ΔE inputted to a gate of an inverter 33 is -G1.ΔE at a drain output of the inverter 33, where -G1 is the amplification factor of the inverter 33 and -G2 is the amplification factor of a clocked gate inverter 36. Moreover, the change is G1.G2.ΔE at the drain output of the clocked gate inverter 36. Since G11 and G21 exist in general, the change in ΔE is amplified very largely and fed back and the feedback is repeated through the same loop, the voltage is converged into a high or a low potential side in a very short time.