Semiconductor memory device of single-bit-line drive type

A semiconductor memory device comprising:

• a plurality of word lines;
• first and second bit lines;
• a plurality of memory cells which are connected to the first and second bit lines, each memory cell having:
• a first inverter having an input terminal and an output terminal;
• a second inverter having an input terminal connected to the output terminal of the first inverter, and an output terminal connected to the input terminal of the first inverter;
• a first transfer-gate transistor having a gate terminal connected to one of the word lines, and a first current path connected at one end to the first bit line and at the other end to at least the output terminal of the first inverter;
• a second transfer-gate transistor having a gate terminal connected to one of the word lines, and a second current path connected at one end to the second bit line and at the other end to at least the output terminal of the second inverter;
• a third transfer-gate transistor having a gate terminal connected to one of the word lines, and a third current path connected at one end to the first bit line;
• and
• a reading-driver transistor having a gate terminal connected to at least the input terminal of the first inverter, and a fourth current path connected at one end to the other end of the third current path of the third transfer-gate transistor, and at the other end to a first power-supply terminal;
• a differential amplifier which is connected to one end of the first bit line and one end of the second bit line;
• a reference-current generating circuit which is connected to the other end of the second bit line and which generates a reference-current smaller than the cell current of the memory cells;
• and
• a dummy word line which is connected to the reference-current generating circuit, to activate the reference-current generating circuit in order to read data.