1. Technical Field
The present invention relates generally to performing a refresh in a memory device, and more particularly to refresh leveraging using multiple strong memory cells for a weak memory cell.
2. Discussion of the Related Art
A volatile memory device, such as a dynamic random access memory (DRAM), performs a refresh operation to retain data stored in memory cells. If a memory cell has a retention time shorter than a refresh period of the refresh operation, a row of memory cells with such a memory cell should be replaced with a row of redundancy cells.
As the size of the memory cell shrinks, the number of memory cells having retention times shorter than the refresh period increases. Accordingly, the number of rows of redundancy cells should be increased in a conventional volatile memory device. However, such a high number of redundancy cells increases the size and complexity of the volatile memory device.