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:
Jul. 01, 2003
Filed:
Dec. 13, 2001
Mohammed A. Hassan, Sugar Land, TX (US);
Robert M. Crosby, Sugar Land, TX (US);
Clyde F. Dunn, Sugar Land, TX (US);
Andrew M. Love, Austin, TX (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
In a Flash memory unit, the storage of a logic signal in the memory cells is determined by performing a READ operation. The NORMAL READ operation requires that the floating gate store an amount of charge Q above which a logic “0” is identified and below which a logic “1” is identified as being stored in the memory cell. A second level of charge Q stored on the floating gate is used in a TEST READ operation. The stored charge Q is greater than the stored charge Q , but less than the charge stored on the floating gate as the result of a WRITE operation. The result of a TEST READ operation is compared with a NORMAL READ operation of a memory cell. When the logic state identified by the TEST READ operation and the NORMAL READ operation are not the same, the charge on the cell is determined to have decayed below a prescribed level and the memory cell is refreshed to the level that is present during a WRITE operation.