CMOS integrated circuit

摘要

A CMOS integrated circuit includes a P-channel type MOS transistor which is formed on an N-type silicon substrate, an N-channel type MOS transistor which is formed on a P well formed in the substrate, and parasitic bipolar transistors which are electrically connected to each other to form a kind of thyristor structure. A power supply voltage is applied to a source electrode of the P-channel type MOS transistor through a part of the substrate which presents a resistance. The resistance is electrically connected to the parasitic bipolar transistor of the thyristor structure to thereby prevent the occurrence of a latch-up phenomenon in which a large current continuously flows through the parasitic bipolar transistors and may destroy the CMOS integrated circuit. Because of the prevention of the latch-up phenomenon, the CMOS integrated circuit is always maintained in good condition.