| 摘要 |
The semiconductor IC has a nonvolatile memory including twin cells, a selector, and a sense circuit. When complementary data are written into a pair of nonvolatile memory cells of each twin cell, the pair of nonvolatile memory cells is set to be in a written state where one cell of the pair is set to one of low and high threshold voltages, and the other is set to the other threshold voltage. When non-complementary data are written into a pair of nonvolatile memory cells, for example, the memory cells both take the low threshold voltage and are made blank. The selector includes switching elements. During the blank-check action, switching elements of the selector are controlled to ON state. Then, the first total current of the twin cells forced to flow into the first input terminal of the sense circuit commonly is compared with the reference signal on the second input terminal, whereby whether the twin cells have been written or blank can be detected at a high speed. As to a semiconductor nonvolatile memory such that complementary data are written into memory cells in memory cell pairs, the blank-check time can be shortened.
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