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A method and device for generating a likelihood ratio soft value for nand flash memory

A technology of likelihood ratio and generalized likelihood ratio, which is applied to the application of multi-bit parity error detection coding, static memory, error correction/detection using block codes, etc., can solve the problem of inaccurate decoding results, Does not have real-time, high complexity and other issues, to achieve the effect of good applicability, easy implementation, and low complexity

Active Publication Date: 2021-04-09
SOUTHWEST JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method uses already translated and outdated data to update the LLR scheme, so it does not have complete real-time performance, high complexity, and poor universality
[0011] In summary, the existing schemes have problems of high complexity and poor applicability, and they cannot adapt well to sudden changes in voltage distribution, resulting in inaccurate decoding results.

Method used

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  • A method and device for generating a likelihood ratio soft value for nand flash memory
  • A method and device for generating a likelihood ratio soft value for nand flash memory
  • A method and device for generating a likelihood ratio soft value for nand flash memory

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specific Embodiment 1

[0063] Under a certain distribution, when the maximum value is taken for all the parameters in the parameter set, the soft value of the likelihood ratio can be calculated using the following formula:

[0064]

[0065] where μ is the desired threshold for the voltage of a state in the memory cell.

specific Embodiment 2

[0067] Under a certain distribution, when the maximum value is taken for one or more parameters in the parameter set, the soft value of the likelihood ratio can be calculated using the following formula:

[0068]

[0069] Among them, κ is the correction factor. In the technical solution of the present invention, the correction factor κ can be obtained through experience or calculation.

specific Embodiment 3

[0071] More generally, the likelihood ratio soft value can be calculated using the following formula:

[0072]

[0073] Among them, F is an arbitrary function constructed by adopting the principle of generalized likelihood ratio.

[0074] In addition, preferably, in a specific embodiment of the present invention, according to the voltage distribution of NAND flash memory in different life cycle sections (for example, different use time period sections, different P / E cycle number sections, etc.) Features, the generalized likelihood ratio soft values ​​with different distribution functions are pre-calculated to form a look-up table, which is pre-stored in the ROM of the read-write controller of the NAND flash memory, and is used for decoding the look-up table in different time periods.

[0075] In addition, in the technical solution of the present invention, a device for generating a soft value of likelihood ratio for NAND flash memory is also proposed. For details, please re...

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Abstract

The invention provides a method and device for generating soft value of likelihood ratio for NAND flash memory. The generating device for the likelihood ratio soft value of the NAND flash memory includes: a read-write controller and an error correction coding iterative decoder. By using the above-mentioned method and device for generating a likelihood ratio soft value for NAND flash memory, a more accurate decoding likelihood ratio soft value can be obtained.

Description

technical field [0001] The present application relates to the technical field of memory, and in particular to a method and device for generating a likelihood ratio soft value for NAND flash memory. Background technique [0002] With the development of electronic technology, more and more memory cells are accommodated per unit area, and the distance between cells is getting smaller and smaller, which also leads to an increase in error rate. [0003] NAND flash memory (NAND Flash) is a non-volatile random access storage medium that has developed rapidly in recent years. The code errors in NAND flash memory are mainly caused by aging caused by the increase in the number of erasing and writing, adjacent unit write interference, and long-term storage. It is caused by effects such as charge loss and read operation distribution. The increase in error rate also greatly reduces the service life of NAND flash memory, for example, when all error control methods cannot guarantee 10 -1...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G11C29/42H03M13/11
CPCG11C29/42H03M13/1108H03M13/1125
Inventor 马征
Owner SOUTHWEST JIAOTONG UNIV