THRESHOLD VOLTAGE SETTING METHOD FOR INVERTER CIRCUIT

PURPOSE:To set an arbitrary threshold voltage by a method wherein the gate length of P-and N-channel transistors is regulated by utilizing the relation of threshold voltage with the voltage between a drain and a source which is determined by a gate layer. CONSTITUTION:A source 21 and a drain 22 of the conductive type reverse to that of a substrate are provided on the surface layer of the N-type semiconductor substrate 10 of an inverter circuit, and a P-channel transistor TR 2 is formed. Also, a well 40 is formed as a reverse conductive region, and the N-channel 4 provided with the source 41 and the drain 42 having the conductive type reverse to that of the well 40 is formed on the internal region. At this time, the gate length Lp on the side of the TR 2 is determined by the interval between the source 21 and the drain 22, and the gate width Wp is determined by the length of the source 21 and the drain 22. Also, the gate length lN and the gate width WN of the TR 4 are determined in the same manner as above, a constant threshold voltage for a wide range of power source voltage is obtained, and the chip of the TR can be made small in size.