Semiconductor device having input protection circuit

摘要

An input protection circuit is formed on a semiconductor substrate. A double well structure is formed by an impurity diffusion region and a protective circuit region containing the input protection circuit. A first potential setting source is connected to a separation region to set a predetermined potential, and a second potential setting source is connected to the semiconductor substrate to set a potential in the semiconductor substrate such that the separation region and the semiconductor substrate are reversely biased. Whereby, the semiconductor substrate including an internal circuit element and a peripheral circuit element is electrically isolated from the double well structure.