Head IC, read circuit, media storage device and amplifier gain adjustment method for head IC

摘要

An amplifier gain adjustment method for a head IC adjusts an amplitude level of a read signal from a head that reads information on a medium. The method includes steps of measuring a resistance value of the head and estimating an output current of the head from the resistance value. An estimated gain value of an AGC amplifier of the head IC constituted by a differential amplifier and an AGC circuit is calculated from a target output value of the AGC amplifier and the output current value. The estimated gain value is set in the AGC amplifier, and the AGC circuit is operated after the estimated gain value is set.