Patent ID: 6512647
Filing Date: 2003-01-28
Classification: G11B

Abstract:
A method of selecting a bias current for a magnetoresistive read head for a disc drive, comprising steps of:(a) identifying a maximum bias current value for the head; (b) identifying a minimum bias current value for the head; (c) defining a tuning range of bias current values based on the maximum and minimum bias current values; (d) iteratively performing a plurality of read operations with the head using a different bias current value for each iteration, the bias current values extending over the tuning range, each iteration producing a result; (e) measuring a read error rate associated with bias current values over the tuning range based on the respective result produced during the respective iteration; (f) identifying the bias current value of each bias current value associated with the lowest read error rate; (g) identifying whether more than one bias current value is associated with the lowest read error rate; and (h) if only one bias current value is associated with the lowest read error rate, selecting the bias current whose value equals the one bias current value, or (i) if more than one bias current value is associated with the lowest read error rate, (i) defining an acceptable range based on the highest and lowest bias current values having the lowest read error rate, and (ii) selecting a bias current value in the acceptable range.