| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a semiconductor memory device in which the stable multi-valued data storage and high speed read-out are attained. <P>SOLUTION: The semiconductor memory device includes first and second cell arrays wherein a plurality of electrically rewritable nonvolatile memory cells are respectively arranged, and a sense amplifier circuit for reading out data of the first and second cell arrays. A plurality of information cells wherein any one among four data levels L0, L1, L2 and L3 (where L0<L1<L2<L3) is written, and at least one reference cell wherein a reference level Lr (where L0<Lr<L1) for detecting the data level is written, are respectively set in the above first and second cell arrays, and the above sense amplifier is constituted so that the data are read out by detecting a cell current difference between the information cell and the reference cell which are simultaneously selected from the first and second cell arrays. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
