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:
Jul. 14, 1987
Filed:
Oct. 21, 1986
Fujitsu Limited, Kanagawa, JP;
Abstract
A semiconductor device such as a TTL-type integrated circuit device which has an input protection circuit for each inner circuit, e.g., each TT logic gate. The input protection circuit is formed on a semiconductor substrate of a first conductivity type, and includes a first impurity region having a second conductivity type connected to an external terminal and an island-shape formed on the semiconductor substrate surrounded by an isolation region having the first conductivity type. The device also includes a clamp diode formed on an electrode layer contacting with the first impurity region. The device further includes a PN junction type protection diode formed on a second impurity region having the first conductivity type; the protection diode crosses the first impurity region between the clamp diode and a portion of the first impurity region connected to the external terminal and reaches the isolation region. The reverse withstand voltage of the PN junction type protection diode is smaller than that of the clamp diode, thereby preventing excessive reverse current flow and avoiding permanent destruction of the clamp diode.