A Threshold Voltage Shift Sensitive Decoding Method for LDPC Codes

Abstract

The invention discloses a threshold voltage drift-aware LDPC code decoding method, comprising: obtaining the current drift parameter of the flash memory page P to which the data to be decoded belongs, so as to obtain the current flash memory according to the corresponding relationship between the threshold voltage distribution of the storage unit and the drift parameter The threshold voltage distribution D of the memory cells in page P; the standard read reference voltage and the voltage at each end point of the threshold voltage distribution D are used as sampling voltages, and the voltage range of the threshold voltage of each memory cell is determined by applying different sampling voltages [v i ,v j ]; According to the voltage range [v i ,v j ] Calculate the soft decision information, and perform LDPC code decoding on the data to be decoded according to the soft decision information; where, the drift parameters include the erasing times and data storage time, v i < v j . The invention can accurately acquire soft decision information by using the drift characteristic of the threshold voltage of the storage unit, thereby improving the decoding performance of the LDPC code and reducing the decoding delay.

Description

technical field [0001] The invention belongs to the technical field of solid-state disk storage, and more particularly relates to a threshold voltage drift-aware LDPC code decoding method. Background technique [0002] Three-dimensional stacked flash memory has the characteristics of high storage density, so it is widely used as a storage device in solid-state disks, smart phones and computer systems. However, high storage density reduces data storage reliability. LDPC code (Low-Density Parity-Check, low-density parity-check code) has a strong error correction capability and is applied to three-dimensional stacked flash memory to ensure data storage reliability. LDPC is a soft-decision error correction code. Before decoding, it needs to use multiple levels to obtain soft-decision information. High-precision soft-decision information can improve decoding performance and reduce decoding delay. In three-dimensional stacked flash memory, in order to obtain high-precision soft ...

AI Technical Summary

Problems solved by technology

In the three-dimensional stacked flash memory, this drift phenomenon is very significant, but the existing flash memory decoding method does not consider the drift characteristics of the threshold voltage of the memory cell in the three-dimensional stacked flash memory when obtaining the soft decision information, which makes the acquired soft decision information The accuracy of decision information is not high, resulting in low decoding performance and high decoding delay, which in turn increases the read overhead of 3D stacked flash memory

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