PURPOSE: To expand the sense voltage range and improve the sensitivity, by using a depression type one for the input MOSFET and setting the threshold voltage of the input MOSFET to a prescribed value.

CONSTITUTION: A depression type one is used for MOSFETs Q1 and Q2 which receive input signals Vin1 and Vin2, and threshold voltages VTH of the Q1 and Q2 are set to, for example, -2VW-3V. When the VTH of the Q1 and Q2 is set to a value which is close to O(zero)V at the negative side, for example, -0.5V, the Q1 is turned ON and the Q2 is turned OFF when the Vin1 becomes O(zero) V and the Vin2 becomes -1V, and the sense operation is performed.