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:
Jun. 04, 2002
Filed:
Jun. 22, 2000
Naoaki Sudo, Tokyo, JP;
Satoshi Katagiri, Kawasaki, JP;
NEC Corporation, Tokyo, JP;
Abstract
A nonvolatile semiconductor device is provided, which does not need excessive writing or verification operations, except for the originally required writing and verification operations. The data is arranged in the order from the lowest “11”, “10”, “01”, to the highest “01”. Four valued writing data are set in the latches and by data signals DL and DL and the latch is initialized to “0”. Writing is executed by three stages, and before writing at each stage, if the latch is “0”, the data is transferred to the latch Writing is only executed when any one latch is “0”, and the latch is changed to “1” after the verification is completed. First, writing is executed up to the threshold value of the data “01”, except the data “11” where the latch is “0”. Next, writing is executed for the data “00” and “01” up to the threshold value of the data “00”, where the latch is “0”. Finally, the data “01” where the latch is “0” is written up to the threshold value of “01”.