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US 2008/0082897 A1Published application
Soft-Input Soft-Output Decoder for Nonvolatile Memory
AssigneeSanDisk Corporation
InventorsYigal Brandman, Kevin M. Conley
Life of this patent
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Abstract
In a nonvolatile memory system, data is read from a memory array and used to obtain likelihood values, which are then provided to a soft-input soft-output decoder. The soft-input soft-output decoder calculates output likelihood values from input likelihood values and from parity data that was previously added according to an encoding scheme.
Claims20
A nonvolatile memory system comprising:
- a memory array including a plurality of cells that store a plurality of data bits and a plurality of parity bits that are calculated from the plurality of data bits according to an encoding scheme;
- a demodulator that reads the plurality of cells and derives raw likelihood values corresponding to the plurality of data bits and the plurality of parity bits;
- and
- a decoder that receives the raw likelihood values and calculates output likelihood values therefrom using the encoding scheme.
1 more element
A nonvolatile memory system comprising:
- a nonvolatile memory array that stores two or more bits in an individual memory cell;
- and
- a demodulator that derives an individual likelihood value for each of the two or more bits stored in the individual memory cell.
A nonvolatile memory system comprising:
- an array of nonvolatile memory cells that are individually programmed to one of two or more threshold voltage ranges that represent two or more states;
- and
- a demodulator that resolves an individual cell threshold voltage to an identified one of the two or more threshold voltage ranges and further resolves the individual cell threshold voltage within the identified threshold voltage range by providing a higher density of read operations for a first portion of the identified threshold voltage range than at for a second portion of the identified threshold voltage range, the demodulator deriving likelihood values from the read operations for the first and second portions.
Dependencies are inferred from the claim text.