AC-driven AMR and GMR magnetoresistors

Anisotropic and giant magnetoresistive (AMR and GMR, respectively) sensors are attractive for industrial applications, as they are more sensitive and stable than Hall sensors. Their performance can be improved by AC excitatio n: flipping for AMR and AC biasing for GMR. AC excitation lowers the hyster esis, reduces the offset and, in some cases, also decreases sensor noise. T he sensitivity to perpendicular fields is reduced in case of AMR sensors. A C-driven magnetoresistors are competitive with miniature fluxgate sensors a nd they are suitable for precise applications such as compasses. (C) 1999 E lsevier Science S.A. All rights reserved.