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:
Oct. 06, 1998
Filed:
Jul. 18, 1997
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
To a column line to which a selected memory cell is connected, a write bias voltage is supplied through a selection gate transistor having different channel conductivity type than the memory cell transistor. Current drivability of the selection gate transistor is adapted to be larger than a leak current of the memory cell and to supply a current smaller than the channel current when a channel is formed in one aspect. When a verifying voltage is applied to the selected word line, a large channel current flows when a channel is formed, potential of a subbit line is changed accordingly, and programming is suppressed. In another aspect, the selection gate transistor serves as a constant current source to make the programming speed of the memory cells constant. Thus distribution of threshold values after programming can be made narrow.