| 摘要 |
<p>PROBLEM TO BE SOLVED: To white, erase stably in a short time by a simple operation, by impressing pulse waves changing to a positive and a negative potentials to a control gate and discharging electric charges accumulated in a floating gate. SOLUTION: A memory cell 1 has a floating gate 3 and a control gate 2, and moreover is connected to a switch MOS transistor 8. A drain electrode of the memory cell 1 is connected to a capacitor 9. The drain electrode of the memory cell 1 is charged to a positive potential 5V and thereafter kept at a floating potential. Then, a positive pulse is impressed to an electrode of the control gate 2 so that a potential is +3V for a short time. A negative pulse is subsequently applied to the electrode of the control gate 2 so that the potential is -10V for a short time. A potential of the floating gate 3 is consequently changed thereby to lower a drain potential. The operation is repeated to reduce electric charges accumulated in the floating gate 3. In this manner, data stored in the memory cell are erased.</p> |
