Method of counting number of cells in nonvolatile memory device and nonvolatile memory device with cell counter performing the same

A nonvolatile memory device comprising:

• a memory cell array including a plurality of memory cells;
• and
• a control circuit configured to:
• set a measurement range and a plurality of measurement intervals of a measurement window for a cell counting operation to a first range and a plurality of first intervals, respectively,
• perform a first sensing operation on first memory cells included in a first region of the memory cell array based on the measurement window,
• perform a first shifting operation for shifting the measurement window while a width of the measurement range and a width of each of the plurality of measurement intervals are maintained,
• perform a second sensing operation on the first memory cells based on the measurement window shifted by the first shifting operation, and
• obtain a final count value for the first memory cells based on a result of the first sensing operation and a result of the second sensing operation,
• wherein the plurality of measurement intervals are included in the measurement range, and
• wherein the control circuit includes:
• an analog-to-digital converter configured to perform an operation of setting the measurement window, the first sensing operation, the first shifting operation and the second sensing operation based on a sensing current obtained from the first memory cells, a reference voltage and a plurality of enable signals;
• a storage configured to store the result of the first sensing operation and the result of the second sensing operation;
• a calculator configured to generate the final count value based on the result of the first sensing operation and the result of the second sensing operation,
• wherein the first shifting operation is performed based on the plurality of enable signals without changing the reference voltage.

A method of counting a number of memory cells in a memory cell array of a nonvolatile memory device, the method comprising:

• setting a measurement range and a plurality of measurement intervals of a measurement window for a cell counting operation to a first range and a plurality of first intervals, respectively, the plurality of measurement intervals being included in the measurement range;
• performing a first sensing operation on first memory cells included in a first region of the memory cell array based on the measurement window having the first range and the plurality of first intervals;
• performing a first shifting operation for shifting the measurement window while a width of the measurement range and a width of each of the plurality of measurement intervals are maintained, the measurement range being set to a second range having a width equal to that of the first range by the first shifting operation, the plurality of measurement intervals being set to a plurality of second intervals having a width equal to that of each of the plurality of first intervals by the first shifting operation;
• performing a second sensing operation on the first memory cells based on the measurement window shifted by the first shifting operation and having the second range and the plurality of second intervals;
• and
• obtaining a final count value for the first memory cells based on a result of the first sensing operation and a result of the second sensing operation,
• wherein the performing of the first sensing operation includes:
• obtaining a first sensing current from the first memory cells;
• obtaining a first count value by comparing the first sensing current with a reference current;
• and
• storing the first count value,
• wherein the performing of the second sensing operation includes:
• obtaining a second sensing current from the first memory cells;
• obtaining a second count value by comparing the second sensing current with the reference current;
• and
• storing the second count value, and
• wherein the obtaining of the final count value includes calculating the final count value based on the first count value and the second count value.