Patent ID: 8223448

Claim:
A disk drive comprising: a disk comprising a plurality of tracks defined by servo sectors, wherein each track comprises a plurality of data sectors; a head actuated over the disk; a preamp circuit operable to amplify a read signal emanating from the head to generate a pre-amplified read signal; and control circuitry comprising a variable gain amplifier (VGA) operable to amplify the pre-amplified read signal to generate an amplified read signal, the control circuitry operable to: calibrate a first gain setting of the preamp circuit in response to a plurality of the servo sectors; adjust the first gain setting in response to a plurality of the data sectors; adjust a second gain setting of the VGA in order to adjust an amplitude of the amplified read signal based on a target response; calibrate the first gain setting of the preamp circuit in response to the second gain setting; wherein: the control circuitry is operable to calibrate the first gain setting in response to the servo sectors by: increasing the first gain setting when the second gain setting is greater than a servo maximum threshold; and decreasing the first gain setting when the second gain setting is less than a servo minimum threshold, the control circuitry is operable to adjust the first gain setting in response to the data sectors by: increasing the first gain setting when the second gain setting is greater than a data maximum threshold; and decreasing the first gain setting when the second gain setting is less than a data minimum threshold; and a range defined by the data maximum threshold and the data minimum threshold is wider than a range defined by the servo maximum threshold and the servo minimum threshold.