Magnetoresistive read nonlinearity correction by a frequency-domain approach

The readback process of a magnetoresistive (MR) head is intrinsically nonlinear. To correct the nonlinearity, a new technique based on a frequency-domain measurement is proposed. In this technique, square-wave patterns of certain frequencies are written as probing signals. The harmonics of the readback signals are then measured and used to derive the coefficients of a correction polynomial. Experimental results show that the correction method significantly reduces the effect of MR saturation on other parametric measurement such as nonlinear transition shift.