Systems and methods for hard error reduction in a solid state memory device
First Claim
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1. A method for writing data to a solid state memory device, the method comprising:
- programming a multi-bit cell of a memory device with a first value selected based upon a first bit value;
reading the multi-bit cell of the memory device using a first selected reference value as a first reference voltage to yield a first read data;
compare the first bit value with the first read data to determine a first bit error rate;
store the first bit error rate;
reading the multi-bit cell of the memory device using a second selected reference value as a second reference voltage to yield a second-read data;
compare the first bit value with the second read data to determine a second bit error rate;
compare the first bit error rate to the second bit error rate and determine which has a lowest bit error rate; and
setting a modified reference value based on a reference value that yields the lowest bit error rate, the modified reference value to be utilized for future writes to the solid state memory device.
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Abstract
Systems and method relating generally to solid state memory, and more particularly to systems and methods for reducing errors in a solid state memory.
67 Citations
20 Claims
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1. A method for writing data to a solid state memory device, the method comprising:
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programming a multi-bit cell of a memory device with a first value selected based upon a first bit value; reading the multi-bit cell of the memory device using a first selected reference value as a first reference voltage to yield a first read data; compare the first bit value with the first read data to determine a first bit error rate; store the first bit error rate; reading the multi-bit cell of the memory device using a second selected reference value as a second reference voltage to yield a second-read data; compare the first bit value with the second read data to determine a second bit error rate; compare the first bit error rate to the second bit error rate and determine which has a lowest bit error rate; and setting a modified reference value based on a reference value that yields the lowest bit error rate, the modified reference value to be utilized for future writes to the solid state memory device. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A data storage system, the system comprising:
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a memory device; a memory device access circuit configured to; program a multi-bit cell of a memory device with a first value selected based upon a first bit value; read the multi-bit cell of the memory device using a first reference value as a reference voltage to yield a read data; select a target voltage for writes to the multi-bit cell of the memory device based upon a combination of a second bit value and the read data; and a reference control circuit configured to modify the target voltage based on a bit error rate of a test region of the memory device. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A flash memory storage system, the system comprising:
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a memory device including a plurality of multi-bit flash memory cells; a memory device access circuit configured to; program a multi-bit flash memory cell of the memory device with a first value selected based upon a first bit value; read the multi-bit flash memory cell of the memory device using a target reference value to yield a read data; program the multi-bit flash memory cell of the memory device with a second value selected based upon a combination of a second bit value and the read data; and a reference control circuit configured to modify the target reference value and configured to; program two or more multi-bit flash memory cells of a selected region of the memory device with a known pattern; read back the two or more multi-bit flash memory cells of the selected region of the memory device using a first test value as a reference voltage to yield a first read back data set; compare the first read back data set with the known pattern; generate a first bit error rate corresponding to the first test value based upon the comparison of the first read back data set with the known pattern; read back the two or more multi-bit flash memory cells of the selected region of the memory device using a second test value as a reference voltage to yield a second read back data set; compare the second read back data set with the known pattern; generate a second bit error rate corresponding to the second test value based upon the comparison of the second read back data set with the known pattern; and select the one of the first test value or the second test value as the target reference value based at least in part on a comparison of the first bit error rate and the second bit error rate. - View Dependent Claims (20)
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Specification