Apparatus and method for providing servo gain linearization for a magneto-resistive head

A hard disk drive, comprising:

• a housing;
• an actuator arm mounted to said housing;
• a head mounted to said actuator arm, said head having a read element;
• a spin motor mounted to said housing;
• a memory device;
• a processor coupled to said head, said actuator arm, said spin motor and said memory device;
• and,
• a disk attached to said spin motor, said disk that having a plurality of tracks, each of said plurality of tracks having a track centerline and a plurality of servo fields, each servo field having an A burst, a B burst, a C burst and a D burst, the A burst and the B burst have a common boundary located at the track centerline and the C burst and the D burst have a common boundary, each of said A, B, C and D bursts providing a corresponding servo burst value;
• wherein said processor directs said read element over the track centerline to sense the A, B, C and D bursts, said processor generating an upper threshold and a lower threshold based on said A, B, C and D servo burst values, said processor generating A′, B′, C′ and D′ servo burst values based on the upper and lower thresholds, said processor further generating a position error signal based on the A′, B′, C′ and D′ upper and lower thresholds and the A, B, C and D servo burst values, the storage device to store said position error signal.

A computer program product, comprising:

• a computer usable medium having computer program code embodied therein to provide a position information signal for a hard disk drive, said hard disk drive having a disk with a plurality of tracks, each of said plurality of tracks having a track centerline and a plurality of servo fields, each servo field having an A burst, a B burst, a C burst and a D burst, the A burst and the B burst have a common boundary located at the track centerline and the C burst and the D burst have a common boundary, each of said A, B, C and D bursts providing a corresponding servo burst value, the computer program product having:
• a) computer readable program code for aligning a read element over the track centerline;
• b) computer readable program code for directing the read element to sense the A, B, C and D bursts;
• c) computer readable program code for generating an upper threshold and a lower threshold based on said A, B, C and D servo burst values;
• d) computer readable program code for generating A′, B′, C′ and D′ servo burst values based on the upper and lower thresholds;
• e) computer readable program code for generating a position error signal based on the A′, B′, C′ and D′ servo burst values and,
• f) computer readable program code for storing said position error signal in a memory device.