| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a data reading out circuit which can perform reading out data under appropriate reference voltage even when a characteristic of an element is varied by the secular change. SOLUTION: When a sample memory cell 10a is selected, a memory transistor 26a in which electrons are not injected to a floating gate is turned on. At the time, voltage V22 is inputted to an input terminal 22 of a sense amplifier 18, a control circuit 13 detects voltage V22 , and stores it as a digital signal. On the other hand, even if a sample memory cell 10b is selected, a memory transistor 26b in which electrons are injected to a floating gate is not tuned on. Therefore, voltage V11 is inputted to the input terminal 22 as it is. A control circuit 13 detects voltage V11 , and stores it as a digital signal. The control circuit 13 sets the reference voltage VREF based on two stored digital signals, and a reference voltage generating circuit 14 generates it.</p> |
