| 摘要 |
PROBLEM TO BE SOLVED: To prevent a gate oxide film from being broken by setting a memory cell transistor to a depletion type and applying a potential that is equal to or less than a power supply potential to a word line on writing/reading. SOLUTION: A word line 3 is set to a power supply voltage VCC by a negative voltage supply circuit 6 using a signal being selected by a row decoder circuit 5, thus turning on a memory cell transistor 1. Then, a GND potential or a power supply potential VCC is applied to a bit line 4. In the case of the GND potential, a capacitor 2 carries GND charge. Therefore, data L carry VCC charge in the case of the power supply voltage VCC so that data are written. In this case, the word line 3 allows the capacitor 2 to retain VCC charge without reducing the potential VCC of the bit line regardless of the influence of backgate effect since the memory cell transistor 1 is in a depletion type regardless of the power supply voltage VCC. |
