Patent ID: 6687066
Filing Date: 2004-02-03
Classification: G11B

Abstract:
In a preamplifier/driver integrated circuit device of the type used to electrically interface with a head of a disc drive and comprising a write current driver circuit to apply write currents to the head to write data in the form of a series of magnetic flux transitions to a recording disc, and a readback signal amplification circuit to apply preamplification to an analog readback signal having peaks corresponding to previously written magnetic flux transitions transduced from the disc, the improvement characterized as an improved preamplifier/driver integrated circuit device further comprising:a prewrite compensation circuit, coupled to the write current driver circuit, which applies prewrite compensation to bits in an input write data stream to adjust timing of magnetic flux transitions written in response to the bits in the input write data stream so that peaks in a subsequent analog readback signal are provided with nominally a same temporal spacing as a temporal spacing of the bits in the input write data stream; an automatic gain control circuit, responsive to the readback signal amplification circuit, which normalizes the subsequent analog readback signal to a desired amplitude range; and an equalizer circuit, responsive to the automatic gain control circuit, which equalizes the normalized subsequent analog readback signal.