Error correction device, error correction method and memory system

Abstract

Error correction is performed with higher precision. The error correction device includes a controller. The controller uses first correspondence information to establish a correspondence between a plurality of readout values ​​and a plurality of probability information contained in the received codeword, and calculates the probability information corresponding to the first received codeword, which is the object of decoding, i.e., the first probability information. The controller performs iterative processing, which repeatedly performs soft-determination decoding using the first probability information until a termination condition is met. If the termination condition is met and the soft-determination decoding fails, the controller performs an update process to update the first correspondence information to second correspondence information. The controller calculates an evaluation value, which is greater when the difference between the first correspondence information and the second correspondence information is larger. The controller performs a change process, which changes at least one of the first parameter used in the iterative processing and the second parameter used in the update process, according to the aforementioned evaluation value; after the change process is performed, iterative processing is performed again.

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