Patent ID: 7859781

Claim:
A head IC, which adjusts an amplitude level of a read signal of a head, and outputs to a read channel having an AGC amplifier, comprising: a differential amplifier for amplifying the read signal by a gain which is set; an AGC circuit that determines a difference between at least one of an input and output amplitude levels of the differential amplifier and a reference level in response to an AGC enable signal from an external device, and automatically controls a gain value of the differential amplifier according to a predetermined lock-in characteristic; an interface unit for receiving a gain value, which is set, from said external device; a switch for selectively setting the gain value of the AGC circuit or the gain value from the interface unit in the differential amplifier in response to the AGC enable signal; and a latch circuit for latching a gain value from the switch and setting the gain value in the differential amplifier.