High quality log likelihood ratios determined using two-index look-up table

摘要

A nonvolatile memory controller includes memory storage configured to store a two-index look-up table that includes a Log-Likelihood Ratio (LLR), hard-and-soft-decision bits associate with the LLR and a neighboring cell read pattern associated with the LLR. Read circuitry is configured to perform a plurality of reads of a cell of a nonvolatile memory storage module at different read voltage levels to generate target cell hard-and-soft-decision bits and configured to read neighboring cells to generate neighboring cell reads. Neighboring cell processing circuitry combines the neighboring cell reads to generate a neighboring cell read pattern. Look-up circuitry accesses the two-index look-up table using the target cell hard-and-soft-decision bits and the neighboring cell read pattern to identify the corresponding LLR for use in Low-Density Parity Check (LDPC) decoding of a codeword stored in the nonvolatile memory storage module.

主权项

1. A method comprising:
storing one or more two-index Log-Likelihood Ratio (LLR) look-up table in a memory controller, the one or more two-index LLR look-up table including a LLR, the hard-and-soft-decision bits associated with the LLR and the neighboring cell read pattern associated with the LLR; performing a plurality of reads of a target cell of a nonvolatile memory storage module at different read voltage levels to generate a plurality of target cell hard-and-soft-decision bits associated with a bit stored in the target cell, wherein the bit stored in the target cell is part of a codeword stored in the nonvolatile memory storage module; performing reads of a plurality of neighboring cells to the target cell of the nonvolatile memory storage module to generate a plurality of neighboring cell reads, each of the neighboring cells in the plurality of neighboring cells adjoining the target cell; combining the results of the neighboring cell reads to generate a neighboring cell read pattern that corresponds to the pattern of the neighboring cell reads; and accessing the one or more two-index LLR look-up table using the plurality of target cell hard-and-soft-decision bits and the generated neighboring cell read pattern to identify the corresponding LLR; and sending the identified LLR to a Low-Density Party Check (LDPC) decoder for decoding of the codeword stored in the nonvolatile memory storage module.