| 摘要 |
An improved dynamic random access memory (DRAM) having self refresh mode is provided. After initiation of a self refresh term Ts, and in a first term Tc1 and a last term Tc2, a concentrated refresh using a refresh clock signal /REFS having a short period Pc is carried out for all rows in a memory cell array. During the remaining term, a normal self refresh operation using a signal /REFS having a long period Ps is carried out. Stored data is maintained effectively because the refresh interval of each row in a memory cell array is prevented from exceeding significantly a predetermined time length Ps.
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