Micromachined CMOS magnetic field sensor with ferromagnetic actuation

In this paper we intend to introduce a new magnetic field sensor. The sensing principle is based on the deformation of a mechanical structure due to magnetic forces, using ferromagnetic materials. Thus the sensor can be classified in the passive sensor category and exhibits very low power consumption, only due to conditioning circuit. The sensor is designed for monolithic integration with CMOS electronics. Post-process fabrication steps are described and experimental results, obtained on a torsion structure are shown. The sensitivity of this new sensor compares with that of highly sensitive Hall plates. A simple analytical model is finally given and turned into analog VHDL description in order to fully integrate the sensor in the standard microelectronic design flow.