According to some embodiments of the present invention, a magnetometer includes at least one sensor for sensing a magnetic field component, a biasing circuit, and a processor. The sensor generates an output signal having a signal characteristic that varies in response to the sensed magnetic field component...http://www.google.com.tw/patents/US6653831?utm_source=gb-gplus-share專利 US6653831 - Magnetometer having a dynamically adjustable bias setting and electronic vehicle compass incorporating the same
