INTEGRATED RESONANT MAGNETIC-FIELD SENSOR

The present paper introduces a magnetic-field sensor based on a resonating single-crystal silicon structure. The excitation of the resonator is achieved by the Lorentz force generated by a sinusoidal current flowing through a rectangular coil deposited on the surface of the structure. The amplitude of the vibration, which is proportional to the magnetic field, is detected by sensing capacitors. A capacitive feedback loop is used to enable the sensor to have a large dynamic range. Because of the high quality factor of the resonator, the expected lower measuring limit is in the nT range. The manufacture of the sensor includes micromachining, glass processing and common bipolar technologies. By adapting these techniques, it is possible to produce sensitive devices at a relatively low unit cost.