| 摘要 |
Additional transistors P1 and P2 which are PMOS transistors are connected to load transistors PL1 and PL2 which are PMOS transistors such that drain electrodes of the additional transistors P1 and P2 and drain electrodes of the load transistors PL1 and PL2 are connected at a node 1 and a node 2 while gate electrodes of the additional transistors P1 and P2 and gate electrodes of the load transistors PL1 and PL2 are connected at the node 1 and the node 2. A source electrode of the additional transistor P1 is connected to an additional transistor control circuit, which is provided for each column. The additional transistor control circuit sets control signals S1 and S2 to the H level in other times than data write so that the additional transistor P1 or P2 compensates the load transistor PL1 or PL2, thereby increasing the static margin. In data write, the additional transistor control circuit sets the control signals S1 and S2 to the low level, thereby preventing the additional transistors from hindering the data write, and thus increasing the write margin.
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