Soft bit data transmission for error correction control in non-volatile memory
First Claim
1. A method of reading non-volatile storage, comprising:
- reading user data from a set of non-volatile storage elements using a first plurality of read compare points, each compare point corresponding to a programmable state of the storage elements;
reading a set of soft data from the set of storage elements at a higher bit resolution than said user data using a second plurality of read compare points having a larger number of read compare points than the first plurality; and
decoding the user data using a first subset of the soft data while reading to determine a second subset of the soft data.
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Abstract
Data stored in non-volatile storage is decoded using iterative probabilistic decoding. An error correcting code such as a low density parity check code may be used. In one approach, initial reliability metrics, such as logarithmic likelihood ratios, are used in decoding sensed states of a set of non-volatile storage element. The decoding attempts to converge by adjusting the reliability metrics for bits in code words which represent the sensed state. Soft data bits are read from the memory if the decoding fails to converge. Initial reliability metric values are provided after receiving the hard read results and at each phase of the soft bit operation(s). In one embodiment, a second soft bit is read from the memory using multiple subsets of soft bit compare levels. While reading at the second subset of compare levels, decoding can be performed based on the first subset data.
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Citations
17 Claims
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1. A method of reading non-volatile storage, comprising:
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reading user data from a set of non-volatile storage elements using a first plurality of read compare points, each compare point corresponding to a programmable state of the storage elements; reading a set of soft data from the set of storage elements at a higher bit resolution than said user data using a second plurality of read compare points having a larger number of read compare points than the first plurality; and decoding the user data using a first subset of the soft data while reading to determine a second subset of the soft data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification