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:
Jan. 14, 1997
Filed:
Nov. 27, 1991
Mitsuru Shimizu, Sakura, JP;
Syuso Fujii, Kawasaki, JP;
Kenji Numata, Yamato, JP;
Masaharu Wada, Yokohama, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
According to the invention, a well region is formed on a semiconductor substrate. An n.sup.+ -type first semiconductor region is formed in the well region, and an input pad for receiving an external signal is connected near the first semiconductor region. This input pad is connected to an input circuit of an integrated circuit constituted by an inverter circuit and to an external terminal for receiving an external signal. N.sup.+ -type second semiconductor regions are formed in the well region located on both sides of the first semiconductor region. A ground potential Vss is applied to these second semiconductor regions. A p.sup.+ -type third semiconductor region is formed around these second semiconductor regions in the well region. The ground potential is applied to the third semiconductor region. Therefore, a parallel circuit formed by a parasitic transistor and a parasitic diode is formed between the input pad and the ground potential. The parasitic transistor is turned on upon electrostatic discharge, and the parasitic diode is turned on when a negative potential for test is applied to the input pad, thereby preventing an erroneous operation of a transistor arranged on the semiconductor substrate.