| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a small-size non-volatile storage device having a verify function by altering a sensing ratio between an output of a verify cell and an output of a reference cell in a sense amplifier. SOLUTION: Non-volatile memory transistors and verify transistors having a memory cell array 11 and a verify cell column 13, in addition to associated circuit elements, are formed on a single semiconductor substrate. A reference cell 16 is also formed simultaneously, so that the same writing/erasing times are achieved with application of the same voltages for writing/erasing information. That is, a change in a threshold value appearing in the memory cell array 11 can be detected by being represented with a change in a threshold value appearing in the verify cell column 13. Accordingly, upon switching to a verify mode, a verify control circuit 18 operates in accordance wit a control signal from a control circuit 20, and an output from the reference cell 16 is amplified by a sensing ratio control circuit 17a to a predetermined level to be then input to a sense amplifier 14.</p> |
