A differential amplifier unit and a feedback unit are provided. The differential amplifier unit includes first and second transistors and first to fourth loads. Each of the first and second transistors is provided with a current input end, a current output end connected to a lower potential power source and a control end. The first and second loads are cascade connected between a higher potential power source and the current input end of the first transistor. The third and fourth loads are cascade connected between the higher potential power source and the current input end of the second transistor. The feedback unit generates first and second feedback currents based on first and second output voltages. The feedback unit inputs the first and second feedback currents to a third node connecting the first and second loads and a fourth node connecting the third and fourth loads.