Decoding method and storage controller

Abstract

A decoding method and a storage controller for a rewritable non-volatile memory module are provided. The method includes: choosing a target word line among a plurality of word lines, wherein preset data is programmed into a plurality of target memory cells of the target word-line; identifying a plurality of preset bit values according to the preset data; respectively using different X read voltage sets to read the target memory cells to obtain X read bit value sets respectively corresponding to the X read voltage sets, and obtain X deviation amount summation sets by comparing the X read bit value sets and the preset bit values; and determining N−1 optimized read voltages of an optimized read voltage set according to the X deviation amount summation sets.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the priority benefit of Taiwan application serial no. 107111392, filed on Mar. 30, 2018. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.BACKGROUND OF THE INVENTIONField of the Invention[0002]The invention relates to a decoding method, and particularly relates to a decoding method and a storage controller for a rewritable non-volatile memory module.Description of Related Art[0003]In general, when data is read from a rewritable non-volatile memory module, if a page reading failure does not occur, the system may read the data according to a default read voltage set or an optimal read voltage set used previously. When a read failure occurs, a system (storage system) may stop using the default read voltage set or the optimal voltage used previously and correspondingly adjust the read voltage set.[0004]In other words, the value of the...

AI Technical Summary

Benefits of technology

[0008]Exemplary embodiments of the invention provide a decoding method and a storage controller capable of quickly and efficiently obtaining an optimized read voltage set precisely corresponding to a target word line. Accordingly, data is read correctly from the target word line by using a plurality of optimized read voltages of the optimized read voltage set, and decoding can be carried out more efficiently.

[0011]Based on the above, in the decoding method and the storage controller according to the embodiments of the invention, the read voltage optimization operation corresponding to the target word line may be performed on the target word line by using the preset data stored in the target word line. In the read voltage optimization operation, the storage controller may calculate the deviation amount summation sets according to the read bit value sets obtained through reading the target word line by using the different read voltage sets, so as to determine the optimized read voltages in the optimized read voltage set corresponding to the target word line according to the deviation amount summation sets. Accordingly, the optimal read voltage set for reading the target word line can be found efficiently and quickly, so as to facilitate the accuracy of the read data and make the decoding for data reading more efficient.

Problems solved by technology

However, known processes for adjusting the read voltage set to obtain the optimal read voltage set are resource-consuming.

In other words, the first conventional process requires a large amount of computing resources (e.g., adjusting the read voltage and verifying corresponding read data) and storage space (e.g., the space for storing preset data).

Thus, decoding becomes less efficient.

Specifically, the read voltages in each of the adjustment read voltage sets cannot be set by the controller of the storage device, and the number of the adjustment read voltage sets is limited.

However, the adjustment read voltage set that is found may not be the optimal read voltage set that meets the current threshold voltage, such as the one found in the first conventional process.

Besides, due to the fewer number of adjustment read voltage sets and the lower accuracy, there may be a circumstance where none of the adjustment read voltage sets reads the data correctly.

In other words, while the second conventional process is able to find out the read voltage set that renders correct data in a more efficient manner than the first conventional process, the chance of failure of the second conventional process is also higher than the chance of the first conventional process.

Thus, how to quickly and efficiently optimize the read voltage without the verified data / preset data to facilitate the reading efficiency and the corresponding decoding efficiency of the rewritable non-volatile memory module is now an issue to work on.

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