Use of alternative value in cell detection
First Claim
1. A method for reading data from a flash memory cell, the method comprising:
- detecting voltages from a group of memory cells, the group of memory cells having associated metadata for error detection, each memory cell storing a voltage representing a data value selected from a plurality of possible data values, each possible data value corresponding to one range of a plurality of non-overlapping ranges of analog voltages;
identifying memory cells having uncertain data values based on the detected voltages;
determining alternative data values for the memory cells having the uncertain data values;
selecting a combination of alternative data values; and
performing an error detection test using the metadata associated with the plurality of memory cells and the selected combination of alternative data values.
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Abstract
A system and method, including computer software, allows reading data from a flash memory cell. Voltages from a group of memory cells are detected. The group of memory cells have associated metadata for error detection, and each memory cell stores a voltage representing a data value selected from multiple possible data values. Each possible data value corresponds to one range of multiple non-overlapping ranges of analog voltages. Memory cells having uncertain data values are identified based on the detected voltages. Alternative data values for the memory cells having the uncertain data values are determined, and a combination of alternative data values is selected. An error detection test is performed using the metadata associated with the multiple memory cells and the selected combination of alternative data values.
168 Citations
32 Claims
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1. A method for reading data from a flash memory cell, the method comprising:
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detecting voltages from a group of memory cells, the group of memory cells having associated metadata for error detection, each memory cell storing a voltage representing a data value selected from a plurality of possible data values, each possible data value corresponding to one range of a plurality of non-overlapping ranges of analog voltages; identifying memory cells having uncertain data values based on the detected voltages; determining alternative data values for the memory cells having the uncertain data values; selecting a combination of alternative data values; and performing an error detection test using the metadata associated with the plurality of memory cells and the selected combination of alternative data values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A system for reading flash memory cells, the system comprising:
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a group of memory cells, each memory cell adapted to receive a charge during a writer operation to a voltage level representing a data value selected from a group of possible data values, each possible data value corresponding to one range of a plurality of non-overlapping ranges of voltages; a set of memory cells associated with the group of memory cells, the set of memory cells adapted to store metadata for correcting errors associated with the group of memory cells; a voltage detector adapted to receive voltage signals from each memory cells; and a processor adapted to; determine alternative data values for each cell having an uncertain data value; select a combination of alternative data values; and use the metadata and the combination of alternative data values to perform error correction. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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24. An article of manufacture comprising machine-readable instructions that, when executed, cause operations to be performed, the operations comprising:
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receiving a voltage signal from a group of memory cells during a read operation, the voltage corresponding to a data value selected from a group of possible data values, each possible data value corresponding to one range of a plurality of non-overlapping ranges of voltages; determining alternative data values for each cell having an uncertain data value; selecting a combination of alternative data values; and performing an error detection test using the metadata to determine if the combination of alternative data values contains an error. - View Dependent Claims (25, 26, 27)
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28. A system for reading flash memory cells, the system comprising:
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a group of memory cells, each memory cell adapted to store a charge representing a data value selected from a group of possible data values, each possible data value corresponding to one of a group of non-overlapping ranges of voltages; a converter for converting the voltage for each memory cell into a digital representation; and means for determining alternative data values for each cell having an uncertain data value; means for selecting a combination of alternative data values; and means for performing error correction on data values stored in the group of memory cells using the selected combination of alternative data values. - View Dependent Claims (29, 30, 31, 32)
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Specification