| 摘要 |
PURPOSE:To simultaneously improve a phase margine and a slice level margine based on a reading signal from a magnetic head by connecting waveform equalizing circuits having respectively different attenuation factors to the prestages of a limiter circuit and a gate generating circuit. CONSTITUTION:A reading signal from a magnetic head is respectively applied to the waveform equalizing circuits 11, 15 and the signal equalized by the circuit 11 is differentiated by a differentiation circuit 12 so that a peak position is converted into a zero crossing point of a differentiated waveform and the output of the circuit is discriminated by a data discriminating circuit 17 through a low-pass filter 13 and a limiter circuit 14. On the other hand, the equalized signal from the circuit 15 is inputted to a gate generating circuit 16 through a low-pass filter 13 and sent to the circuit 17. In this case, the waveform equalizing effects of the circuits 11, 15 are different from each other and the attenuation factors are also different. In a phase margine system based on the waveform equalizing circuits, the attenuation factors are set up so that the sum of an S/N jitter value and a pattern peak shifting value is minimized. In a slice level margine system, the attenuation factors are set up so that the sum of voltage dropping rates due to S/N ratios is minimized.
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