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:
Aug. 19, 1997
Filed:
Jun. 28, 1996
Naoaki Sudo, Tokyo, JP;
Toshio Takeshima, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
In a nonvolatile semiconductor memory, in addition to a first voltage generating circuit for supplying various voltages to memory cell transistors in various operations, there is provided a second voltage generating circuit for supplying various voltages to a dummy cell in a reference voltage generating circuit in the various operations. The second voltage generating circuit is configured to supply a dummy cell writing voltage to the dummy cell, one time only when the erase operation for the memory cell transistors has been carried out. Accordingly, with a very simple construction, the progress of the deterioration of the dummy cell and the memory cell transistor can be made close to each other, so that the working life of the nonvolatile semiconductor memory can be lengthened.