| 摘要 |
A sense amplifier band arranged between two memory cell arrays includes sense amplifiers, and spare memory cells usable as backup spare memory cells for memory cells included in the memory cell arrays. Using the spare memory cells, a refresh operation is executed while being divided into two stages. Namely, refresh target data read to sense amplifiers is temporarily stored in one of the spare memory cells, read again and written to the original memory cell. As a result, high rate operation is realized at low cost and area penalty is small.
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