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. 05, 1998
Filed:
Aug. 22, 1996
Makoto Takahashi, Yokohama, JP;
Kazutaka Nogami, Ichikawa, JP;
Kabushiki Kaisha Toshiba, Kawasaki, JP;
Abstract
In the output buffer circuit, when an enable signal is inputted to deactivate the main buffer circuit (MB1) and further when a voltage higher than the first supply voltage V.sub.DD is applied to the output terminal (I/O), since the fifth P-type transistor (QP2) is turned on, the voltage at the output terminal is applied to the gate of the third P-type transistor (QP1), so that this transistor (QP1) is perfectly turned off. Therefore, it is possible to prevent unnecessary current from flowing from the output terminal (I/O) to the first supply voltage (V.sub.DD) terminal through the third P-type transistor (QP1). Further, since the sixth P-type transistor (QP4) is turned on, the voltage at the output terminal is applied to the gate of the second P-type transistor (QP6) through the sixth P-type transistor (QP4), so that this transistor (QP6) can be perfectly turned off. Therefore, it is possible to prevent unnecessary current from flowing to the first supply voltage (V.sub.DD) terminal through the first and second P-type transistors (QP5 and QP6). Further, since a voltage higher than the first supply voltage will not be applied to the gate oxide film of the second to sixth P-type transistors all formed on the same N-type substrate, it is possible to prevent the manufacturing process from being complicated.