| 摘要 |
An EFM-signal comparator which superposes a direct voltage on an input EFM signal, and produces a square wave of a predetermined duty cycle (50% typically) by comparing the superposed signal of the direct voltage and the input EFM signal with a predetermined threshold voltage. The signal comparator having a primary direct-voltage-output circuit which produces a direct voltage corresponding to the "1" level duration of the square wave, a secondary direct-voltage-output circuit which produces a direct voltage corresponding to the "0" level duration of the square wave, a switching circuit which outputs either the direct voltage from the primary direct-voltage-output circuit or the direct voltage from the secondary direct-voltage-output circuit, a voltage-output circuit which outputs a voltage corresponding to the direct voltage outputted from the switching circuit, and a smoothing circuit which smoothes and superposes the voltage outputted from the voltage-output circuit on the input EFM signal. The EFM-signal comparator can be integrated into an LSI except for large-scale wave-smoothing capacitors, because all of the other components are small enough to be manufactured by CMOS, while the large-scale wave-smoothing capacitors are too large to be produced by CMOS.
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