Abstract
Magnetic position sensors are transducers whose output is an electrical signal that is a function of a mechanical motion. They consist of a permanent magnet, a magnetic field sensor, and a moving magnetic circuit. Being contactless, they do not wear out. Unlike optical systems, they are impervious to contamination. With the proliferation of microprocessor control in many on-board automotive applications, magnetic position sensing becomes a crucial function, found e.g. in cam and crankshaft sensors used for ignition timing and engine misfire detection, in brushless electrical motors, in wheel speed sensors and in other applications. This paper first reviews the requirements put on the magnetic field sensors in these applications. Five main types of field sensors are used: Si Hall sensors with integrated amplifiers, GaAs Hall sensors, InSb-based magnetoresistors, anisotropie magnetoresistors (AMR), and metal-multilayer magnetoresistors (GMR). Magnetoresistors are almost always used as differential pairs, either in Wheatstone bridges or with matched constant current sources. The two characteristics of each type of field sensors that matter most are their sensitivity to magnetic field, and the smallest amount of field modulation they can detect, i.e. their resolution, which is mainly limited by the drift of the outputs with temperature. These parameters are measured and reported here on the 5 types of sensors; the work is an update of a 1993 review by the author.
Similar content being viewed by others
References
H. Weiss, Structure and Applications of Galvanomagnetic Devices, Pergamon Press, Oxford, 1969
Magnetic Sensors, Data Book, Siemens Aktiengesellschaft, Baianstrasse 73, D-8000 Muenchen, Germany, 1989 and 1996
J. Heremans, Magnetic Devices, Encyclopedia of Applied Physics, VCH Publishers Inc., 1993
J. Heremans, Solid state magnetic field sensors and applications, J. Phys. D: Appl. Phys 26 1149(1993)
K. Ota and T. Hashimoto, Society of Automotive Engineers, Transaction No. 930 551 (1993)
R.G. Mani and K. von Klitzing, Appl. Phys. Lett. 64 3121 (1994); R.G. Mani, K. von Klitzing, F. Jost, K. Marx, S. Lindenkreuz and H. P. Trah, Appl. Phys. Lett. 67 2223 (1995)
Data sheet 27501.1, and Integrated and Discrete Semiconductors, Data Book, Allegro Microsystems, Inc., 115 Northeast Cutoff, Box 15036, Worchester, MA 01615, USA, 1995
EMCORE Corporation, 394 Elizabeth Ave., Somerset, NJ 08873, USA
J. Heremans, Semicond. Sci. Technol. 8 S424 (1993)
Honeywell, Magnetic Products, Solid State Electronics Center, 12001 State Highway 55, Plymouth, MN 55441, USA
Integrated GMR Magnetic Sensors, NVSI, Nonvolatile Electronics Inc., 11409 Valley View Road, Eden Prairie, MN 55344
Dale L. Partin and Joseph P. Heremans, U.S. Patent No. 5,184,106 (2 Feb. 1993)
Dale L. Partin and Joseph P. Heremans, U.S. Patent No 5,153,557 (6 Oct. 1992)
Acknowledgement
technological advantages they offer, was made possible by a close collaboration with T. Schroeder, D. L. Partin, C. M. Thrush, L. Green, B. K. Fuller and Bruno Lequesne. Production of lnSb magnetoresistors was made possible by L. Koszi, M. Brown and E. Douglas.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Heremans, J.P. Magnetic Field Sensors for Magnetic Position Sensing in Automotive Applications. MRS Online Proceedings Library 475, 63–74 (1997). https://doi.org/10.1557/PROC-475-63
Published:
Issue Date:
DOI: https://doi.org/10.1557/PROC-475-63