ERROR RECOVERY STORAGE ALONG A NAND-FLASH STRING
First Claim
1. A method of storing error recovery data for a NAND flash memory array having two or more levels, the method comprising:
- storing data with a block error correction code using a first level of multiple-level cells and along a first dimension of the NAND flash memory array; and
storing data with a supplemental error correction code using a second level of the multiple-level cells and along a second dimension of the NAND flash memory array, wherein the supplemental error correction code is incrementally updateable.
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Accused Products
Abstract
Apparatus and methods store error recovery data in different dimensions of a memory array. For example, in one dimension, block error correction codes (ECC) are used, and in another dimension, supplemental error correction codes, such as convolutional codes, are used. By using separate dimensions, the likelihood that a defect affects both error recovery techniques is lessened, thereby increasing the probability that error recovery can be performed successfully. In one example, block error correction codes are used for data stored along rows, and this data is stored in one level of multiple-level cells of the array. Supplemental error correction codes are used for data stored along columns, such as along the cells of a string, and the supplemental error correction codes are stored in a different level than the error correction codes.
199 Citations
41 Claims
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1. A method of storing error recovery data for a NAND flash memory array having two or more levels, the method comprising:
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storing data with a block error correction code using a first level of multiple-level cells and along a first dimension of the NAND flash memory array; and storing data with a supplemental error correction code using a second level of the multiple-level cells and along a second dimension of the NAND flash memory array, wherein the supplemental error correction code is incrementally updateable. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of recovering data from a NAND flash memory array, the method comprising:
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reading a page of data from a first selected row of the memory array; performing block decoding of error correction codes of the page of data; determining that error exists after block decoding of the page of data; and decoding supplemental error correction codes relating to the first selected row to recover the page of data, wherein the supplemental error correction codes are arranged along columns of the memory array, wherein the supplemental error correction codes are incrementally updateable. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
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18. An apparatus comprising:
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an interface circuit configured to receive data intended for storage to a memory device and to communicate with the memory device, wherein data for the memory device is stored in rows and columns of a NAND flash memory array, and wherein cells of the NAND flash memory array store data in at least two levels; and a supplemental error correction coder circuit coupled to the interface circuit, the supplemental error correction coder circuit configured to compute supplemental error correction codes by columns of data, wherein the supplemental error correction codes are incrementally updateable. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. An apparatus comprising:
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an interface circuit configured to receive data intended for storage to a memory device and to communicate with the memory device, wherein data for the memory device is stored in rows and columns of a NAND flash memory array, and wherein cells of the NAND flash memory array store data in at least two levels; and a supplemental decoder circuit coupled to the interface circuit, the supplemental decoder circuit configured to decode supplemental error correction codes to recover data, wherein the supplemental error correction codes are incrementally updateable. - View Dependent Claims (29, 30, 31, 32)
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33. An apparatus comprising:
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a NAND flash memory array having rows and columns, wherein each cell of the NAND flash memory stores at least two bits of data, wherein data is written to and read from the NAND flash memory array in rows; a supplemental error correction coding circuit configured to compute supplemental error correction codes by columns of normal data; and a supplemental decoding circuit configured to decode supplemental error correction codes stored in the NAND flash memory array to recover data, wherein the supplemental error correction codes are incrementally updateable. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41)
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Specification