Bias Method for Magnetoresistive Sensors
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-01
A conventional magnetic biasing method for a magnetoresistive (MR) head element is combined with an AC biasing method to reproduce a signal spectrum free of intermingled distortion products. Magnetic bias is generally produced by a DC sense current achieved by a shunt conductor, a permanent magnet or a soft magnetic film in close proximity to the MR element. The static or DC magnetic field component causes the quiescent point of the MR element to be shifted to a linear portion of the parabolic curve of the MR transfer characteristic. Then a high frequency sinusoidal waveform is superimposed on the DC field through the sense conductors to the MR element. The DC sense current prevents crossing of the zero field point. For operation, the signal field to be read from the media must be less than one-third of the AC bias frequency.