Offset-centering, a way towards higher resolution of Hall-sensor-signals

Characteristic curves of Hall-sensors typically have high offsets. Especially if magnetic flux parallel to the surface of the Substrate has to be measured, the integrated (vertical) sensors have offsets in a range of several tens or a few hundred mT. There are many attempts to get rid off the offset using offset-cancellation methods. The 'Spinning-Current'-method is obviously not the only but the most effective one. But all these methods don't solve the problem, that usually the offset is much larger than the magnetic Signal itself. So the maximum gain of the preamplifier, which can be chosen to keep the signal within the input range of the following stages, is not limited by the Signal but by the initial offset of the device. The aim of the new 'Offset-Centering' method, which is presented in this paper, is to reduce the offset of the Single phases of the spinning-current method systematically in a way that the intrinsic offset cancellation scheme of the Spinning-Current method is not disturbed but the usable gain of the preamplifier can be increased. This means, that the input range of the analog to digital converter can be used more efficiently.