公开(公告)号：JPH08306794A

公开(公告)日：1996-11-22

申请号：JP9344496

申请日：1996-03-22

Applicant: CONS RIC MICROELETTRONICA

Inventor： NATAARE AIERO ,  BUITSUTO GURATSUIAANO

IPC: H01L27/06 ,  H01L21/8222 ,  H01L27/02 ,  H03K17/735

Abstract: PROBLEM TO BE SOLVED: To ensure a timely response when the voltage of an isolated region clamped by a switch is rapidly changed by maintaining the isolated region with a reference potential, and instructing the opening of the switch. SOLUTION: When the potential of a region 1 (SUB) is rapidly dropped to a ground potential by capacity coupling, the potential of an isolated region 2 (ISO) is dragged toward a negative voltage value. The dynamic potential movement of the region 2 is detected by a comparator COMP beyond a reference voltage clamped by a switch T, and the switch T is opened by changing the state. The region 2 is turned into a high impedance state against a floating or ground node according to the opening of the switch T, and as a result, the region potential is turned into a free state by capacitive coupling C1 and C2, and the decreased voltage of the substrate region 1 is tracked by presenting a negative voltage value. Thus, the region 2 can be biased to the potential presented by the substrate region 1, and allowed to stay with a negative potential.