An anisotropic magneto resistive sensor with set/reset field.

Using a set/reset magnetic field, an anisotropic magneto resistive (AMR) magnetic field sensing system was developed to reduce the low frequency noise of an AMR sensor. The magnetic field resolution of the AMR sensor was improved by about three times at the frequencies below 30 Hz and a magnetic field resolution of about 150 pT/√Hz was obtained at 1 Hz. For magnetic particle detection using an AMR sensor with set/reset method, the thermal disturbance effect was canceled well and the signal-to-noise ratio was improved by about three times.