The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 25, 2003
Filed:
Sep. 27, 2000
Tsukasa Ohoka, Shiga, JP;
NEC Corporation, Tokyo, JP;
Abstract
An input protection circuit comprising a MOS transistor which has a P type semiconductor layer provided with an N type drain region of rectangular shape and a P type backgate contact region surrounding the same, the P type backgate contact region having the shape of a frame parallel to each side of the drain region. In the input protection circuit, negative-level static electricity applied to an electrode pad is discharged by means of a forward bias to the PN junction between the semiconductor layer and the drain region. Here, N type diffusion layers of U shape are formed between the drain region and the backgate contact region in the semiconductor layer at a predetermined distance from the drain region, so as to surround the vicinities of both longitudinal ends of the drain region. Thereby, the current path through the forward-biased PN junction is partially increased in resistance to avoid local current concentration for improved breakdown voltage.