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:
Nov. 15, 2011
Filed:
Nov. 29, 2007
Hiroki Tanigami, Fukuyama, JP;
Masahiro Saitoh, Fukuyama, JP;
Takayuki Taniguchi, Kitakatsuragi-gun, JP;
Hiroki Tanigami, Fukuyama, JP;
Masahiro Saitoh, Fukuyama, JP;
Takayuki Taniguchi, Kitakatsuragi-gun, JP;
Sharp Kabushiki Kaisha, Osaka-shi, JP;
Abstract
A semiconductor memory device comprises a memory cell array including memory cells arranged in matrix each having a selective transistor and a variable resistance element having an electric resistance changed from a first state to a second state by applying a first write voltage and from the second state to the first state by applying a second write voltage. A first write current for a first writing operation to change the electric resistance from the first state to the second state is larger than a second write current for a second writing operation to change it from the second state to the first state. A second memory cell number of memory cells subjected to the second writing operation at a time is greater than a first memory cell number of memory cells subjected to the first writing operation at a time. At least the second memory cell number is plural.