| 摘要 |
PURPOSE:To obtain a high reliable reference value suitable for an actual signal by generating the reference value at a serial signal period depending on the upper limit and the lower limit of the serial signal period detected from a parallel signal supplied externally. CONSTITUTION:The upper limit and the lower limit of the serial signal period of a parallel signal 1 are detected respectively by an upper limit deciding circuit 2 and a lower limit deciding circuit 3 and a reference value generating circuit 6 generates a reference value 7 based on the upper limit value 4 and the lower limit value 5. Then a comparison circuit 8 compares the parallel signal 1 at the serial signal period with the reference value 7 signal, and when the signal is larger than the reference value 7, an H level is outputted as a serial signal 9 and when the signal is smaller than the reference value 7, an L level is outputted as the signal 9.
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