| 摘要 |
PROBLEM TO BE SOLVED: To provide a magnetometer having an electromechanical resonator 102 coupled to a drive-and-detect (DD) circuit, in one embodiment. SOLUTION: The resonator is provided with a deformable beam which is a part of a closed current path. When a periodic drive signal is applied to a driving electrode disposed near the deformable beam, the DD circuit causes the oscillation of the beam. In the presence of a magnetic field, a magnetic flux passing through the closed current path is varied by the oscillation, and an oscillation current is thereby generated in the current path. When the current is consumed by the resistive loss in the closed current path, the oscillation of the deformable beam is dampened, wherein the attenuation coefficient depends on the intensity of the magnetic field. The DD circuit using a sensing electrode disposed near the deformable beam detects the amplitude of the oscillation. Based on the detected amplitude, the frequency of the driving signal is varied by the DD circuit, for finding the resonance frequency. Because the resonance frequency depends on the damping coefficient, the intensity of the magnetic field can be comparatively easily deduced from the resonant frequency. COPYRIGHT: (C)2006,JPO&NCIPI
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