Abstract : A two-axis MEMS magnetometer with integrated signal processing has been developed for a micro-compass application. The fabrication process is fully industrial and relies on bulk wet etching of CMOS dies. This technology offers cost- effective batch fabrication. Earth magnetic field measurement is achieved using piezoresistive gauges on a cantilever beam actuated by means of the Lorentz force. Due to low signal level available across the gauges, on-chip amplification with very high gain and low noise is then required. A fully differential amplifier based on a differential pair is suitable for this application. Circuit design approach is discussed in this paper. The obtained performances in terms of noise are compared to an instrumentation amplifier. Finally, a sensing resolution of 0.9 μT is demonstrated with such a differential amplifier instead of 2.1 μT resulting from standard-cell based instrumentation amplifier.
https://hal-lirmm.ccsd.cnrs.fr/lirmm-00269472
Contributor : Christine Carvalho de Matos
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Submitted on : Thursday, April 3, 2008 - 8:12:15 AM
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Norbert Dumas, Laurent Latorre, Pascal Nouet. Low Noise CMOS Amplifier for a Piezoresistive Magnetic Field Sensor. DCIS: Design of Circuits and Integrated Systems, Nov 2003, Ciudad Real, Spain. pp.639-644. ⟨lirmm-00269472⟩
