Patent ID: 8634228

Claim:
A driving method of a semiconductor device, the semiconductor device comprising: a memory cell comprising a first transistor, a capacitor and a second transistor, wherein a gate of the first transistor is electrically connected to one electrode of the capacitor and a source of the second transistor; a selection transistor, wherein a source of the selection transistor is electrically connected to a drain of the first transistor and a drain of the selection transistor is electrically connected to a drain of the second transistor; a bit line electrically connected to a drain of the selection transistor and the drain of the second transistor; a selection line electrically connected to a gate of the selection transistor; a writing word line electrically connected to a gate of the second transistor; a reading word line electrically connected to the other electrode of the capacitor; and a source line electrically connected to a source of the first transistor, the driving method comprising the steps of: supplying a potential to the bit line; supplying a potential to the writing word line to turn on the second transistor, whereby a potential is supplied to the one electrode of the capacitor from the bit line; supplying a potential to the selection line to turn off the selection transistor; and supplying a potential to the source line to turn on the first transistor, whereby a charge corresponding to the potential to the bit line is accumulated in the gate of the first transistor and the one electrode of the capacitor, wherein the potential to the source line is lower than a threshold value of the first transistor to turn on the first transistor.