Volatile memory device capable of relieving disturbances of adjacent memory cells and refresh method thereof

A volatile memory device comprising:

• a cell array including a plurality of DRAM cells;
• a disturbance detector configured to count a number of accesses to a first memory area of the cell array and generate a detect signal when the number of the counted accesses reaches a reference value;
• a refresh control logic configured to, in response to the detect signal, perform a refresh operation on a second memory area and a third memory area of the cell array, each being located adjacent to the first memory area;
• and
• an alert generator configured to, in response to the detect signal, output an alert signal from the volatile memory device to an outside of the volatile memory device.

A method of operating a memory device including a memory cell array, the method comprising:

• counting a number of times that a first set of memory cells of the memory cell array is accessed during a first time period;
• when the counted number of times equals to a reference number is detected, activating an alert signal for a period of time and outputting the alert signal from the memory device to the outside of the memory device;
• and
• performing a refresh operation on a second set of memory cells of the memory cell array,
• wherein the second set of memory cells is located adjacent to the first set of memory cells.