| 摘要 |
<p>PROBLEM TO BE SOLVED: To read out turned off cells at a high rate by disposing a half bank select transistor at a position dividing a diffusion line into two in the column direction and performing selective blocking depending on the position of the word line of a cell to be read out. SOLUTION: Diffusion lines A, B, C,... for connecting each drain and source of cells SX1, SX2,..., respectively, with bit line terminals D0, D1,... and imaginary ground line terminals VG0, VG1,... are divided by half bank select transistors HTI, HT2 depending on the upper and lower stages of word lines W0, W1,... At the time of reading out the cell SX1 of the upper stage word line W0, bank select transistors BT2, BT3 are turned on to feed the bit line terminal D1 with a sense amp current. In this regard, the half bank select transistors HT1, HT2 are turned, respectively, off and on selectively. Even if the cell SX1 is turned off and adjacent cells SX2, SX3 are turned on, the lower stage parts of diffusion lines F, H are not charged.</p> |
