| 摘要 |
An apparatus for detecting off-track positioning of a disk read/write head seeking a selected data track on a disk having data tracks with embedded servo burst patterns recorded thereon. The apparatus comprises a compare and select component, a charge redistribution A/D converter circuit and an off-track controller. The compare and select component compares and selects from among voltage values corresponding to the servo bursts a pair best representing track centerline as a first servo signal and a second servo signal and determines which of the servo signals is greater. The charge redistribution analog-to-digital (A/D) converter circuit determines if the normalized track position exceeds a position threshold representing a percentage of the normalized track position distinguishing on-track from off-track position through the use of an internal binary-weighted, switched capacitor array DAC and a comparator. The DAC receives as inputs the first servo signal and the second servo signal and has an array of binary-weighted, switched capacitors, which is configured according to a position threshold-related value. The binary value of the position threshold is supplied by the off-track controller. Based on the output of the DAC, the comparator determines whether or not an off-track condition has occurred. Once an off-track condition has been detected, the off-track controller generates an off-track position error signal in response to the comparator output when indicative of an off-track condition.
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