Off-Resonance Low-Pressure Operation of Lorentz Force MEMS Magnetometers

This paper demonstrates bandwidth extension for Lorentz force microelectromechanical systems magnetometers operated at a frequency slightly lower than the mechanical resonance. This off-resonance mode of operation also minimizes the critical tradeoff between maximum sensing bandwidth and minimum measurable field, enabling low-pressure operation and the associated resolution improvement. The experimental verification is obtained using two identical devices packaged at two different pressures and tested with a suitable low-noise board-level electronics. The first device, packaged at 1 mbar, has a (mechanical) sensing bandwidth of ~50 Hz, and a resolution per unit bandwidth and driving current of 290 nT · mA/√Hz. With the second device, packaged at 0.25 mbar and operated off-resonance, roughly twice better resolution (160 nT · mA/√Hz) and four times larger bandwidth (>200 Hz) are obtained.

[1]  Christian Schott,et al.  A CMOS Single-Chip Electronic Compass with Microcontroller , 2007, 2007 IEEE International Solid-State Circuits Conference. Digest of Technical Papers.

[2]  H. Emmerich,et al.  Magnetic field measurements with a novel surface micromachined magnetic-field sensor , 2000 .

[3]  Giacomo Langfelder,et al.  The Dependence of Fatigue in Microelectromechanical Systems on the Environment and the Industrial Packaging , 2012, IEEE Transactions on Industrial Electronics.

[4]  David A. Horsley,et al.  Resonant MEMS magnetometer with capacitive read-out , 2009, 2009 IEEE Sensors.

[5]  Volker Kempe.  Inertial MEMS: Gyroscopes , 2011 .

[6]  A.A. Trusov,et al.  Environmentally Robust MEMS Vibratory Gyroscopes for Automotive Applications , 2009, IEEE Sensors Journal.

[7]  Aarne Oja,et al.  A 3D micromechanical compass , 2008 .

[8]  Robert Neal Dean,et al.  Applications of Microelectromechanical Systems in Industrial Processes and Services , 2009, IEEE Transactions on Industrial Electronics.

[9]  Guillaume Jourdan,et al.  Electromechanical damping in MEMS accelerometers: A way towards single chip gyrometer accelerometer co-integration , 2014, 2014 IEEE 27th International Conference on Micro Electro Mechanical Systems (MEMS).

[10]  M. J. Thompson,et al.  Low power 3-axis Lorentz force navigation magnetometer , 2011, 2011 IEEE 24th International Conference on Micro Electro Mechanical Systems.

[11]  F. Ayazi,et al.  Wafer-level vacuum-packaged triaxial accelerometer with nano airgaps , 2013, 2013 IEEE 26th International Conference on Micro Electro Mechanical Systems (MEMS).

[12]  Ernesto Lasalandra,et al.  $Z$-Axis Magnetometers for MEMS Inertial Measurement Units Using an Industrial Process , 2013, IEEE Transactions on Industrial Electronics.

[13]  George T. Flowers,et al.  A Characterization of the Performance of a MEMS Gyroscope in Acoustically Harsh Environments , 2011, IEEE Transactions on Industrial Electronics.

[14]  R. Etienne-Cummings,et al.  Practical considerations for the use of a Howland current source for neuro-stimulation , 2008, 2008 IEEE Biomedical Circuits and Systems Conference.

[15]  Salvatore Sessa,et al.  Towards Miniaturization of a MEMS-Based Wearable Motion Capture System , 2011, IEEE Transactions on Industrial Electronics.

[16]  Samuel Huber,et al.  CMOS Single-Chip Electronic Compass With Microcontroller , 2007, IEEE Journal of Solid-State Circuits.

[17]  Giacomo Langfelder,et al.  Operation of Lorentz-Force MEMS Magnetometers With a Frequency Offset Between Driving Current and Mechanical Resonance , 2014, IEEE Transactions on Magnetics.

[18]  P. Ripka,et al.  Precise AMR magnetometer for compass , 2003, Proceedings of IEEE Sensors 2003 (IEEE Cat. No.03CH37498).

[19]  Alberto Corigliano,et al.  On-Chip Mechanical Characterization using an Electro-thermo-mechanical Actuator , 2010 .

[20]  L. Sousa,et al.  2-Axis Magnetometers Based on Full Wheatstone Bridges Incorporating Magnetic Tunnel Junctions Connected in Series , 2012, IEEE Transactions on Magnetics.

[21]  Guizhen Yan,et al.  A monolithic inertial measurement unit fabricated with improved DRIE post-CMOS process , 2010, 2010 IEEE Sensors.