SEMICONDUCTOR MEMORY DEVICE, ITS READ-OUT METHOD, AND ELECTRONIC EQUIPMENT

摘要

PROBLEM TO BE SOLVED: To perform read operation which has high reliability in a nonvolatile memory array.

SOLUTION: Each memory cell has a pair of memory parts in which information is read using first and second current paths being inverse directions each other. A current flowing in each memory cell indicates distribution 93 to 96 shown in a figure in accordance with memory states [00][01][10][11] of the memory cell in each current path. A first reference current level 91 is decided between the distribution 93 and the distribution 95, a second current level 92 is decided between the distribution 94 and the distribution 96. A current flowing in the memory cell is compared with reference current levels 91, 92 in the first and the second current paths, while electric charges corresponding to the current flowing the memory cell are accumulated respectively in first and second accumulation parts. Quantity of electric charges accumulated in the first accumulation part is compare with quantity of electric charges accumulated in the second accumulation part.

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