Semiconductor memory device with error checking and correcting function
First Claim
1. A semiconductor memory device comprising:
- a memory cell array including a plurality of memory cells arranged in rows and columns;
selection means responsive to an address signal for simultaneously selecting a predetermined constant number of memory cells in said memory cell array, each of the simultaneously selected memory cells being arranged both on a different row and on a different column with respect to other selected memory cells in said memory cell array for any address designated by said address signal; and
reading means for reading out data of all of the simultaneously selected memory cells.
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Accused Products
Abstract
A memory cell array is divided into a plurality of subregions along row and column directions. In data reading, 1-bit memory cell is selected from each of the subregions which are arranged on different rows and different columns in this memory cell array. Data are simultaneously read from the simultaneously selected memory cells. The simultaneously read data include information bits and at least one error checking bit. Only data of a 1-bit memory cell is read from one word line at the maximum. Thus, it is possible to extremely reduce a probability that two or more erroneous data bits are included in a plurality of bits of simultaneously read data even if a selected word line is defective. It is possible to execute error checking and correction in accordance with an ECC scheme, improving repairability for defective bits in a semiconductor memory device.
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Citations
16 Claims
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1. A semiconductor memory device comprising:
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a memory cell array including a plurality of memory cells arranged in rows and columns; selection means responsive to an address signal for simultaneously selecting a predetermined constant number of memory cells in said memory cell array, each of the simultaneously selected memory cells being arranged both on a different row and on a different column with respect to other selected memory cells in said memory cell array for any address designated by said address signal; and reading means for reading out data of all of the simultaneously selected memory cells. - View Dependent Claims (2, 3, 4, 5)
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6. A semiconductor memory device comprising:
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a memory cell array including nonvolatile memory cells being arranged in a matrix of rows and columns, said memory cell array being divided into the same number of blocks along directions of said rows and said columns to have a plurality of subregions; a plurality of word lines being arranged in correspondence to said rows of said memory cell array, each said word line being connected with a row of said memory cells; a plurality of bit lines being arranged in correspondence to said columns of said memory cell array, each said bit line being coupled with a column of said memory cells; a plurality of sub source lines each being coupled with a prescribed number of cells of said memory cells; a plurality of main source lines being arranged in correspondence to respective said subregions, each said main source line being connected with sub source lines provided in a corresponding subregion in common; word line selection means for selecting a plurality of word lines included in different subregions in said column direction in response to a supplied address signal; source line selection means for simultaneously selecting a plurality of main source lines being provided in different subregions in said row and column directions from said plurality of subregions in response to the supplied address signal; bit line selection means for selecting a plurality of bit lines one from each of said subregion being divided in said row direction in response to the supplied address signal; and means for reading data from memory cells being arranged in correspondence to intersections of the selected word lines, the selected bit lines and the sub source lines being connected to the selected main source lines. - View Dependent Claims (7, 8, 9)
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10. A semiconductor memory device comprising:
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a memory cell array including a plurality of memory cells arranged in a matrix of rows and columns for storing information in a nonvolatile manner, a prescribed number of cells of said memory cells being serially arranged to form a unit, said memory cell array being divided into a plurality of regions along directions of said rows and said columns; a plurality of word lines arranged in correspondence to respective said rows; a plurality of bit lines arranged in correspondence to respective said columns; a plurality of source lines arranged in correspondence to said prescribed number of memory cells, each said unit having said prescribed number of memory cells serially connected between a corresponding source line and a corresponding bit line; word line selection means for simultaneously selecting a plurality of word lines contained in different ones of said regions divided along said column direction from said plurality of word lines in response to a supplied address; bit line selection means for selecting a bit line from respective ones of said regions divided along said row direction in response to the supplied address signal; and source line selection means for forming a current path between a corresponding bit line and a corresponding source line for each of said units of said memory cells in response to the supplied address, said source line selection means including means for forming said current paths for the units of said memory cells provided in different subregions from each other in both said row and column directions. - View Dependent Claims (11, 12)
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13. A method of reading out data from a semiconductor memory device having a memory cell array including a plurality of memory cells arranged in rows and columns, comprising the steps of:
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selecting a plurality of rows in said memory cell array in response to a first address signal; selecting a plurality of memory cells on the selected rows and on different columns in response to a second address signal, one memory cell from each of the selected rows, each of the selected memory cells being arranged on a different column with respect to other selected memory cells for any address designated by said second address signal; reading data of the selected memory cells for error checking and correction; and supplying data externally after the error checking and correction. - View Dependent Claims (14, 15, 16)
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Specification