| 摘要 |
Disclosed is an AGC circuit, used for read channels of a disk storage apparatus, for controlling a level of a reading output of a head to be kept constant. This AGC circuit has a gain control amplifier (3) and a feedback circuit (6,7,8,9) for digitally feeding back an output thereof. A maximum current value of a current type D/A converter (7) 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 (7) 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 (7) 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. |
