SYSTEM AND METHODS EMPLOYING MOCK THRESHOLDS TO GENERATE ACTUAL READING THRESHOLDS IN FLASH MEMORY DEVICES
First Claim
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1. A method for reading at least one page within an erase sector of a flash memory device, the method comprising:
- computing at least one mock reading threshold;
using said at least one mock reading threshold to perform at least one mock read operation of at least a portion of at least one page within said erase sector, thereby to generate a plurality of logical values;
defining a set of reading thresholds based at least partly on said plurality of logical values; and
reading at least one page in said erase sector using said set of reading thresholds.
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Abstract
A method for reading at least one page within an erase sector of a flash memory device, the method comprising computing at least one mock reading threshold; using the at least one mock reading threshold to perform at least one mock read operation of at least a portion of at least one page within the erase sector, thereby to generate a plurality of logical values; defining a set of reading thresholds based at least partly on the plurality of logical values; and reading at least one page in the erase sector using the set of reading thresholds.
205 Citations
19 Claims
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1. A method for reading at least one page within an erase sector of a flash memory device, the method comprising:
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computing at least one mock reading threshold; using said at least one mock reading threshold to perform at least one mock read operation of at least a portion of at least one page within said erase sector, thereby to generate a plurality of logical values; defining a set of reading thresholds based at least partly on said plurality of logical values; and reading at least one page in said erase sector using said set of reading thresholds. - View Dependent Claims (2, 3, 5, 6, 9, 10, 11, 12, 13, 14, 15, 19)
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4. A method for rapidly assessing functionality of erase sectors in a flash memory, the method comprising:
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estimating a mean and standard deviation of at least one physical level over at least a portion of at least one page belonging to an erase sector of a flash memory device; wherein said estimating is performed for at least a first physical level residing above a second physical level and below a third physical level and wherein estimating the mean and standard deviations of said first physical level comprises interpolating between previously found means and standard deviations of said second and third levels.
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7. A method for assessing effects of retention and cycling on individual erase sectors in a flash memory which has undergone retention and cycling, the method comprising:
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receiving a first centerpoint of a rightmost lobe of a distribution of physical values within the cells of a new flash memory device and a second centerpoint of a rightmost lobe of a distribution of physical values within the cells of an entirely degraded flash memory device; generating a histogram representing distribution of physical values within the cells of an individual erase sector, over a range extending at least between said second and first centerpoints; and computing at least one statistic of a rightmost lobe of the histogram. - View Dependent Claims (8)
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16. A system for reading at least one page within an erase sector of a flash memory device, the system comprising:
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mock threshold computation apparatus operative to compute at least one mock reading threshold; a reading threshold set generator operative to define a set of reading thresholds based at least partly on said plurality of logical values; and reading apparatus using said at least one mock reading threshold to perform at least one mock read operation of at least a portion of at least one page within said erase sector, thereby to generate a plurality of logical values and subsequently using said set of reading thresholds based at least partly on said plurality of logical values to read at least one page in said erase sector using said set of reading thresholds.
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17. A system for rapidly assessing functionality of erase sectors in a flash memory, the system comprising:
flash memory physical level distribution statistic estimation apparatus estimating a mean and standard deviation of at least one physical level over at least a portion of at least one page belonging to an erase sector of a flash memory device and including interpolation apparatus, wherein said apparatus receives and operates upon at least a first physical level residing above a second physical level and below a third physical level by using said interpolation apparatus to interpolate between previously found means and standard deviations of said second and third levels.
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18. A system for assessing effects of retention and cycling on individual erase sectors in a flash memory which has undergone retention and cycling, the system comprising:
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a histogram generator operative to generate a histogram representing distribution of physical values within the cells of an individual erase sector, over a range extending at least between a first centerpoint of a rightmost lobe of a distribution of physical values within the cells of a new flash memory device and a second centerpoint of a rightmost lobe of a distribution of physical values within the cells of an entirely degraded flash memory device; and a rightmost lobe analyzer operative to compute at least one statistic of a rightmost lobe of the histogram.
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Specification