A method of calibrating parameters of an apparatus for measuring a back electromotive
force (BEMF) of a voice coil motor (VCM) for moving a head on a disk, the apparatus
including the VCM having a coil resistance Rm, a coil inductance Lm, and a sensing
resistance Rs, including: controlling the VCM to sequentially perform a track following
operation of the head on a first track, a transferring operation of the head from
the first track to a second track, and a track following operation of the head
on the second track; sampling a differential voltage Vadc between a voltage across
the VCM and a voltage across the sensing resistance Rs and a VCM driving current
Im during the transferring operation; calculating a slope S based on a ratio of
a first integration value to a second integration value, where the first integration
value is obtained by integrating a product of the sampled differential voltage
Vadc and the VCM driving current Im during the transferring operation, the second
integration value being obtained by integrating a square of the VCM driving current
Im during the transferring operation, the slope S being defined by the equation
S=Rm-GbRs, Gb being a gain of an amplifier for amplifying the voltage across
the sensing resistance Rs; and calibrating the parameters of the apparatus using
the slope S.