A new technique of noise reduction for large aspect magnetoresistors

A large aspect (width to thickness ratio) magnetoresistive sensor operated with an alternating transverse biasing is characterized by high sensitivity and reduced temperature drift. However, it has little demagnetizing anisotropy to maintain a single domain state so noisy behavior often results. A constant longitudinal field can be used to reduce this noise but at the expense of reduced sensitivity. A new unipolar a.c. longitudinal biasing technique is presented which allows the full sensitivity to be achieved whilst significantly reducing magnetic noise and hysteresis