| 摘要 |
<p>PURPOSE:To keep the value of writing current almost constant by changing the gate voltage of a write control MOS TR or column selecting MOS TR in accordance with the value of the writing current. CONSTITUTION:A high voltage VP due to a decoded output X is impressed to the gate of a memory cell 11 and injected into an electron floating gate at the generation of impact ionization to write data. At that time, large current is made to flow into a course consisting of a resistor 21, MOS TRs 13, 12 and the memory cell 11. When the current is made to flow into the resistor 21, a potential difference is generated between both the ends of the resistor 21 and a voltage VA smaller than the VP is obtained from a serial node 22. If the current flowing into the resistor 21 is constant, the voltage VA is also constant, output voltage VB from a control circuit 30 is also fixed and the ON resistance value of the MOS TR13 is also fixed, so that the constant current is kept as it is.</p> |
