| 摘要 |
<p>PURPOSE:To enable correct setting of plural reference levels required at the time of reading by generating (N-1) kinds of reference levels necessary for discriminating N kinds of multiple value levels of a memory cell by a dummy cell. CONSTITUTION:The content of memory of N kinds of lavels, such as three values of a memory cell 1 of a word line 3 selected by a row selecting circuit 4' and a column selecting circuit 5' is inputted to (N-1) sets, two sets etc., of comparator circuits through a selected data line 2 and the circuit 5', and compared with each of (N-1)kinds, 2 sets etc., of reference voltage from dummy cells 1', 1'' of a word line 3' that passes through a data line 2', circuit 5', and multiple values such as three values of the cell 1 are read out. By this constitution in which reference levels affected by driving of circuits 4', 5' similarly to memory level are used, correct setting of reference levels at the time of reading can be made easily.</p> |
