Flipping field and stability in anisotropic magnetoresistive sensors

Switched-capacitor flipping circuits developed for Philips KMZ51 and KMZ52 anisotropic magnetoresistance (AMR) sensors give up to 2.8 A/1 kHz current peaks. Such unusually high current deeply saturates the sensor and thus removes hysteresis, reduces noise, and increases the resistance against field shocks. These necessary strong flipping fields are predicted by the energetic model (EM), applied to the magnetization reversal in thin films. The EM parameters have been correlated to microscopic variables, revealing the field dependence of the speed of magnetization reversal. This is responsible for the value of the critical switching field (and therefore for the stability of the AMR sensor) in the easy axis directions, depending on the saturating field amplitude.