Method for refreshing a memory device, in which the victim row refresh operation is hidden in the normal refresh operation without affecting the time allocated for the normal refresh operation

A method for refreshing a memory device, wherein the memory device comprises a plurality of memory banks, the method comprising:

• dividing the memory banks at least into a first group and a second group;
• and
• performing a normal refresh operation on the first group and the second group sequentially;
• wherein during a period where the normal refresh operation is performed on one of the first group and the second group, a victim row refresh operation is performed on a victim row of the other one of the first group and the second group,
• wherein a time allocated to the victim row refresh operation performed on the victim row of the other one of the first group and the second group is shorter than a time allocated to the normal refresh operation performed on the one of the first group and the second group,
• wherein the victim row refresh operation is hidden without affecting either the frequency of the normal refresh operation and the time allocated to the normal refresh operation for each refresh command.