Methods and devices to reduce outer code failure rate variability
First Claim
1. A method of encoding and storing data in a solid state memory device, comprising:
- encoding data into inner code words corresponding to pages of the memory device that are sequentially accessed in a particular order;
selecting pages for page groups that reduce failure rate variability of outer codes of the page groups, each outer code including outer code parity; and
encoding the page groups into the outer codes and storing the encoded page groups in the memory device, wherein encoding the page groups and storing the encoded page groups includes intermittently accumulating the outer code parity for each of the page groups as the pages are sequentially stored in the memory device according to the particular order.
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Accused Products
Abstract
The variability of outer code failure rate of memory pages of a solid state memory device can be reduced by selectively grouping the pages included in the outer code words. The data in the page groups are encoded into outer code words which are stored in the memory device. Encoding the data of the page groups and storing the encoded data includes intermittently accumulating an outer code parity as the pages are sequentially stored in the memory device according to a particular order. The pages can be randomly selected for the page groups or can be grouped based on predicted or measured failure rate information. In a memory device having multi-level memory cells, predicting the failure rate of a page can be based on whether the page is a most significant bit (MSB) page or a least significant bit (LSB) page.
17 Citations
19 Claims
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1. A method of encoding and storing data in a solid state memory device, comprising:
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encoding data into inner code words corresponding to pages of the memory device that are sequentially accessed in a particular order; selecting pages for page groups that reduce failure rate variability of outer codes of the page groups, each outer code including outer code parity; and encoding the page groups into the outer codes and storing the encoded page groups in the memory device, wherein encoding the page groups and storing the encoded page groups includes intermittently accumulating the outer code parity for each of the page groups as the pages are sequentially stored in the memory device according to the particular order. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of operating a solid state non-volatile memory device having multi-level memory cells configured to store more multiple bits of data, the method comprising:
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encoding data into inner code words, the inner code words arranged according to MSB pages comprising most significant bits (MSBs) of the memory cells and LSB pages comprising least significant bits (LSBs) of the memory cells, the MSB and LSB pages sequentially accessed in a particular order; encoding page groups of MSB pages and LSB pages into outer codes, each page group having a substantially equal number of MSB pages and LSB pages; and storing the encoded page groups in the memory device, wherein encoding the page groups and storing the encoded page groups includes intermittently accumulating the outer code parity for each of the page groups as the pages are sequentially stored in the memory device according to the particular order. - View Dependent Claims (10)
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11. A solid state memory device comprising:
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an inner encoder configured to encode data into inner code words arranged according to pages of the memory device, the pages associated with failure rate information; page grouping circuitry configured to group the pages into page groups to reduce variability in outer code failure, wherein each of the page groups includes a substantially equal number of most significant bit (MSB) pages and least significant bit (LSB) pages; an outer encoder configured to encode the pages of the page groups into outer codes, the outer encoder including a parity generator configured to intermittently accumulate the outer code parity for each of the page groups as the pages are sequentially stored in the memory device according to the particular order; and modulator circuitry configured to store the encoded pages in memory cells of the memory device. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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Specification