Abstract: A Schmitt circuit comprises a series connection of a first, second and third MOS transistors connected between a voltage source and the ground, and a fourth MOS transistor connected between the voltage source and the junction of the second and third MOS transistors. An input voltage is applied to the gates of the second and third MOS transistors. The voltage at the junction of the first and second MOS transistors is applied to the gate of the fourth MOS transistor and is also led out as an output. The Schmitt circuit further comprises a series connection of a sixth and seventh MOS transistors connected between the voltage source and the ground for dividing the source voltage, and a fifth MOS transistor connected between the junction of the sixth and seventh MOS transistors and the junction of the first and second MOS transistors and adapted to be rendered conductive when the potential at the said junction exceeds a predetermined voltage.