Semiconductor memory device having mode storing one bit data in two memory cells and method of controlling same

摘要

A device has a bit line pair including first and second bit lines, a sense amplifier commonly connected to the bit line pair, and first and second cells connected at intersecting portions of first and second word lines and the first and second bit lines. In a normal mode, the first and second word lines are assigned separate addresses, whereas in a partial mode, the first and second word lines are assigned the same address. The first and second cells complimentarily store one bit of data. In storing a data in a first cell of two cells comprised in a twin cell into a second cell when set to the partial mode, the second word line is activated based on a trigger signal generated by a refresh timer during a precharge period for the bit line pair, and subsequently the precharge is completed. The first word line is then activated based on a delayed signal of the trigger signal, and the sense amplifier is activated to amplify a differential voltage between the bit line pair, so that the data of the first cell is written back into the first and second cells.