Flash memory, flash memory system and operating method of the same
First Claim
1. A method of operating a flash memory comprising a plurality of memory cells, the method comprising:
- defining a first adjacent threshold voltage range and a second adjacent threshold voltage range for a first pair of threshold voltage distributions adjacently located;
counting the number of memory cells having threshold voltages included in the first adjacent threshold voltage range by subtracting the number of the memory cells having a threshold voltage lower than a first search read voltage from a number of the memory cells having a threshold voltage lower than a first reference read voltage;
counting the number of memory cells included in the second adjacent threshold voltage range by subtracting the number of the memory cells having a threshold voltage lower than the first reference read voltage from the number of the memory cells having a threshold voltage lower than a second search read voltage; and
setting a first optimal read voltage based on a count difference between the counted number of the memory cells having the threshold voltages included in the first adjacent threshold voltage range and the counted number of the memory cells having the threshold voltages included in the second adjacent threshold voltage range,wherein setting the first optimal read voltage based on the count difference, is performed by calculating using a result value generated from applying a first adjustment parameter to the count difference, wherein the first adjustment parameter is a slope of a tangent at the origin of a graph representing the count difference verses a threshold voltage of the memory cells.
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Abstract
A flash memory, a flash memory system, and an operating method thereof. The method of operating a flash memory includes counting the number of memory cells having threshold voltages included in a first adjacent threshold voltage range (defined by a first reference read voltage for distinguishing between initially separated adjacently located threshold voltage distributions and a first search read voltage having a first voltage difference from the first reference read voltage), and a second adjacent threshold voltage range (defined by the first reference read voltage and a second search read voltage having a second voltage difference from the first reference read voltage), and setting a first optimal read voltage based on the difference between the first and second counted numbers of the memory cells.
18 Citations
19 Claims
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1. A method of operating a flash memory comprising a plurality of memory cells, the method comprising:
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defining a first adjacent threshold voltage range and a second adjacent threshold voltage range for a first pair of threshold voltage distributions adjacently located; counting the number of memory cells having threshold voltages included in the first adjacent threshold voltage range by subtracting the number of the memory cells having a threshold voltage lower than a first search read voltage from a number of the memory cells having a threshold voltage lower than a first reference read voltage; counting the number of memory cells included in the second adjacent threshold voltage range by subtracting the number of the memory cells having a threshold voltage lower than the first reference read voltage from the number of the memory cells having a threshold voltage lower than a second search read voltage; and setting a first optimal read voltage based on a count difference between the counted number of the memory cells having the threshold voltages included in the first adjacent threshold voltage range and the counted number of the memory cells having the threshold voltages included in the second adjacent threshold voltage range, wherein setting the first optimal read voltage based on the count difference, is performed by calculating using a result value generated from applying a first adjustment parameter to the count difference, wherein the first adjustment parameter is a slope of a tangent at the origin of a graph representing the count difference verses a threshold voltage of the memory cells. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of operating a flash memory comprising a plurality of memory cells, comprising:
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respectively counting the number of memory cells having threshold voltages included in a first adjacent threshold voltage range and a second adjacent voltage range defined by a first reference read voltage and a pair of first search read voltages having a first voltage difference and a second voltage difference from the first reference read voltage, respectively; and setting a first optimal read voltage based on a result value generated by applying an first adjustment parameter to the difference between the number of memory cells having threshold voltages within the first adjacent threshold voltage range and the number of memory cells having threshold voltages within the second adjacent threshold voltage range, wherein the memory cells are multi-level cells arranged vertically from a substrate, wherein the first adjustment parameter is a slope of a tangent at the origin of a graph representing the difference verses a threshold voltage of the memory cells.
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15. A memory device comprising:
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a memory cell array including a plurality of memory cells; and an on-chip controller configured to set a first optimal read voltage for the memory cell array in response to an external control signal, the on-chip controller comprising; a counter configured to count the number of memory cells included, respectively, in a first adjacent threshold voltage range and a second adjacent threshold voltage range, defined by a first reference read voltage and by a pair of first search read voltages respectively having a first voltage difference and a second voltage difference from the first reference read voltage; and a control logic configured to set the first optimal read voltage based on a result value generated by applying a first adjustment parameter to a difference between the number of memory cells having threshold voltages included within the first adjacent threshold voltage range and the number of memory cells having threshold voltages included within the second adjacent threshold voltage range, wherein the first adjustment parameter is a slope of a tangent at the origin of a graph representing the difference verses a threshold voltage of the memory cells. - View Dependent Claims (16, 17, 18, 19)
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Specification