| 摘要 |
PURPOSE:To reduce a bit error rate, and to raise reliability of a magnetic disk device by constituting so that a frequency characteristic of a differentiating circuit used for a reproducing circuit is varied in accordance with a track position of a magnetic head. CONSTITUTION:An N channel junction gate field effect transistor 13 connected in series with a capacitor 12 is added in parallel to a capacitor 9. The gate of this FET13 is connected to an output of a D/A converter 14. A signal 15 for showing an information of a track position of a magnetic head is inputted to the converter 14, power is outputted in accordance with a track position of a magnetic head, and a resistance (rDS) between the drain and the source of the FET 13 is varied in accordance with said power. That is to say, the rDS is controlled by a track position of the magnetic head. Accordingly, a differentiating circuit having a frequency characteristic which is suitable for each track position is obtained by setting appropriately the output voltage of the converter 14. |
