Magnetic field sensor

An AMR sensor, comprises at least first and second AMR sensor elements to which opposite bias fields are applied. The first and second AMR sensor element outputs are combined to derive a sensor response which is substantially anti-symmetric in the region close to zero external magnetic field. This arrangement shifts the zero detection point of the AMR sensor elements away from a maximum of the response curve, so that sensitivity in proximity to a zero input field is obtained. To overcome the problem that the response is not anti-symmetric, the signals from (at least) two sensor elements are combined.