Micromachined CMOS magnetic field sensors with low-noise signal conditioning

Two original electromechanical magnetic sensors have been developed using fully industrial fabrication process that relies on bulk wet etching of CMOS dies. The first device uses the Lorentz force to actuate a U-shaped cantilever beam, while piezoresistive polysilicon gauges convert the beam bending into electrical signal. A 2/spl mu/T sensor resolution has been achieved, making this device suitable for earth magnetic field measurement. The second prospective device uses a ferromagnetic material deposited on top of a free standing mechanical frame. Such approach leads in the design of a passive sensor that does not require any electrical power for actuation.