| 摘要 |
<p>PURPOSE:To facilitate the control of a threshold by setting up input data in accordance with the size of a threshold voltage to be set up in one memory cell and feeding back an output consisting of plural bits which corresponds to the written threshold voltage to change the threshold until the plural bits of the output and the input coincide with each other. CONSTITUTION:A chain line part 18 compares the potential of a point (b) to be changed in accordance with the threshold voltage with the reference levels of C1-C3 and outputs one of 4 kinds of combinations of two-bit outputs Dout0, Dout1,. When the values of Din0 and Din1 are writing status, a signal S is turned to ''0''. If a signal WRITE is ''0'', writing is executed. When a signal READ is turned to ''1'', writing is interrupted. In the reading status, voltage corresponding to the writing is outputted on the point (b) and the outputs Dout0 and Dout1 are determined in accordance with the voltage value. The value is fed back and compared with the Din0 and Din1 by comparator 7, 8. If both the values coincide with each other, the writing is stopped, and in case of inconsistency, the writing is executed and the result is fed back.</p> |
