PURPOSE: To prevent electric characteristics of paired MOSFETs from being affected from the manufacture process by generating hysteresis characteristics with the paired MOSFETs of the same manufacture process.

CONSTITUTION: The gm ratio when the level of an input IN is inverted depends on the NMOSFETs 14, 15 and also on the PMOSFETs 13, 16 and the width of hysteresis depends on pairs of the FETs 14, 15 and FETs 13, 16. Thus, the FETs of each pair are manufactured by the same manufacture process.