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:
May. 04, 1999
Filed:
Apr. 02, 1998
George J Korsh, Redwood City, CA (US);
Sakhawat M Khan, Sunnyvale, CA (US);
Agate Semiconductor, Inc., Sunnyvale, CA (US);
Abstract
An integrated circuit memory system having memory cells capable of storing multiple bits per memory cell is described. The memory system has a restoring operation in which a memory cells' stored charge, which may drift from its initially set condition, is maintained within one of a plurality of predetermined levels corresponding to digital bits of information and defined by a set of special reference voltage values. The memory system has mini-programming and mini-erasing operations to move only the amount of charge into and out of the memory cell sufficient to keep the charge within the predetermined levels. The memory system also has an operation for high speed programming of the memory cells and an erasing operation to narrow the charge distribution of erased memory cells for increasing the spread, and safety margins, between the predetermined levels.