摘要 |
An AGC circuit is used for read channels of a disk storage apparatus, by controlling a level of a reading output of a head to be kept constant. This AGC circuit has a gain control amplifier and a feedback circuit for digitally feeding back an output thereof. A maximum current value of a current type D/A converter is varied for every zone in zone bit recording. A gain adjusting time of the AGC circuit can be therefore minimized in each zone. A GAP length in the respective zones can be thereby reduced, and a storage capacity is increased. A maximum current value of the current type D/A converter is varied in a read/write area and a data surface servo area on a disk storage medium. It is therefore feasible to minimize the gain adjusting time of the AGC circuit in each of the servo area and the read/write area. The current type D/A converter is set so that a plus-side maximum current value is different from a minus-side maximum current value. The operation is therefore speeded up when increasing a gain, and the gain adjusting time of the AGC circuit can be minimized.
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