Abstract: A first write transistor has a source connected to a power-supply node, a drain connected to a first local bit line, and a gate connected to a second write global bit line. A second write transistor has a source connected to the power-supply node, a drain connected to a second local bit line, and a gate connected to a first write global bit line. A third write transistor has a source connected to the first write global bit line, a drain connected to the first local bit line, and a gate receiving a first control signal. A fourth write transistor has a source connected to the second write global bit line, a drain connected to the second local bit line, and a gate receiving the first control signal. A read circuit is connected to the first and second local bit lines and first and second read global bit lines.

Abstract: A dummy bit line is provided between a pair of bit lines. The pair of bit lines is set at a power supply voltage and the dummy bit line is set at a ground voltage, and then the pair of bit lines and the dummy bit line are equalized. When a word line is activated in subsequent read operation, the pair of bit lines is at an intermediate potential lower than the power supply voltage, so that an apparent current drive capability of an access transistor decreases, and the static noise margin of a memory cell increases.

Abstract: A dummy bit line is provided between a pair of bit lines. The pair of bit lines is set at a power supply voltage and the dummy bit line is set at a ground voltage, and then the pair of bit lines and the dummy bit line are equalized. When a word line is activated in subsequent read operation, the pair of bit lines is at an intermediate potential lower than the power supply voltage, so that an apparent current drive capability of an access transistor decreases, and the static noise margin of a memory cell increases.