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:
May. 15, 1984
Filed:
Dec. 04, 1981
Shigenobu Taira, Aizuwakamatsu, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
An input protection circuit which protects the gate of a MIS transistor from breakdown due to an excessively high voltage being applied thereto. The input protection circuit includes a first resistor and a second resistor connected in series between a input terminal and a gate of the MIS transistor, a first protection transistor provided between a first connecting point between the first and second resistors and one side of the power supply, and a second protection transistor provided between a second connecting point between the second resistor and the gate of the MIS transistor the other side of the power supply. The first protection transistor has a large mutual conductance gm, while the second protection transistor has a low breakdown voltage. With this input protection circuit, even when the gate breakdown voltage of the transistor to be protected is lower than the breakdown voltage of the first protection transistor, the gate electrode is kept at a voltage lower than the gate breakdown voltage by means of the second protection transistor having a lower breakdown voltage.