Bad column handling in flash memory
First Claim
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1. A nonvolatile memory system comprising:
- a memory array having a plurality of columns, each of the plurality of columns comprising one or more bit lines; and
a soft-input error correction code decoder configured to receive hard data and soft data for at least one bad column of the plurality of columns and further configured to decode the hard data in combination with the soft data to generate decoded data,wherein the soft data comprises compressed information including indication of locations of bad data within the at least one bad column, andwherein the locations of bad data are replaced by indications of low likelihood.
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Abstract
In a flash memory, redundant columns are used alternatively as replacement columns for replacing bad columns or to provide additional redundancy for ECC encoding. Locations of bad columns are indicated to a soft-input ECC decoder so that data bits from bad columns are treated as having a lower reliability than data bits from other columns.
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Citations
10 Claims
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1. A nonvolatile memory system comprising:
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a memory array having a plurality of columns, each of the plurality of columns comprising one or more bit lines; and a soft-input error correction code decoder configured to receive hard data and soft data for at least one bad column of the plurality of columns and further configured to decode the hard data in combination with the soft data to generate decoded data, wherein the soft data comprises compressed information including indication of locations of bad data within the at least one bad column, and wherein the locations of bad data are replaced by indications of low likelihood. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification