The Effect of Non-linear MR Read-back Distortion on a PRML Channel

Abstract

An effect of non-linear readback process of an MR head on a PRML digital magnetic recording channel was studied. Although combination of a highly sensitive MR read head and a PRML channel is promising for high areal density recording, non-linearity in the MR readback process is a critical issue for the channel in which linearity is inherently assumed. First, we theoretically analyzed the characteristics of SHD (Second Harmonic Distortion) as a figure of merit of the non-linearity. Next, the effect of non-linearity on error rates was studied by computer simulation and examined by experiments. Results show that SHD of less than -25 dB is required for the channel in order to be rid of the non-linear distortion.