A magnetic field sensor is an entrance transducer that converts a magnetic field into an electronic signal. Semiconductor magnetic field sensors exploit the galvanomagnetic effects due to the Lorentz force on charge carriers. Integrated semiconductor, notably silicon, magnetic field sensors, are manufactured using integrated circuit technologies. Integrated sensors are being increasingly developed for a variety of applications in view of the advantage offered by the integration of the magnetic field sensitive element together with support and signal processing circuitry on the same semiconductor chip. The ultimate goal is to develop a broad range of inexpensive batch-fabricated high-performance sensors interfaced with the rapidly proliferating microprocessor. This review aims at the recent progress in integrated silicon magnetic devices such as integrated Hall plates, magnetic field-effect transistors, vertical and lateral bipolar magnetotransistors, magnetodiodes, and current-domain magnetometers. The current development of integrated magnetic field sensors based on III-V semiconductors is described as well. Bulk Hall-effect devices are also reviewed and serve to define terms of performance reference. Magnetic device modeling and the incorporation of magnetic devices into an integrated circuit offering in situ amplification and compensation of offset and temperature effects are further topics of this paper. Silicon will continue to be aggressively exploited in a variety of magnetic (and other) sensor applications, complementary to its traditional role as integrated circuit material.

Integrated semiconductor magnetic field sensors

A description is given of a general approach for producing high-resolution tactile sensors that are highly compliant. The approach is based on the idea of compliance matching, wherein the high compliance of the contacting element is matched to the low compliance of the sensing element. A prototype tactile sensor is proposed which uses magnetic fields as the matching medium. The author details the design of an important component of this device, 64*64 element array of magnetic field sensors. >

A magnetic field based compliance matching sensor for high resolution, high compliance tactile sensing

Integrated silicon magnetic-field sensors

The authors present a novel, fully integrated magnetic field sensor made in the standard, polysilicon-gate CMOS technology. The circuit shows a sensitivity of 1.2 V/T with 10 V supply voltage and 100 /spl mu/A current consumption. The circuit consists of a pair of split-drain MOS transistors in a CMOS-differential amplifier-like configuration.

A CMOS magnetic field sensor

Recent silicon magnetic sensors and integrated sensors are described. The silicon magnetic sensors, whose fabrication is compatible with the standard IC process, are in the limelight because they can easily be incorporated into integrated circuits and it may be possible to realize intelligent sensors. However, although there are some cases of successful integrated magnetic sensors on the market, such as the Hall IC, their function is too simple to call them intelligent sensors. In this paper the present situation is described, and attention is focused on the coming intelligent sensors.

Integrated magnetic sensors

A structure has been devised which converts magnetic flux density change to a change in output current. The structure is essentially a P-channel MOST with the drain diffusion split into two halves. A magnetic field normal to the silicon surface deflects device current towards one half-drain. By operating the MOST in the "pinched-off" mode (V DS > V GS -V T ) the output impedance is made high, so that large output voltage swings may be obtained. A theoretical study of the voltage and current distributions in the MOST channel has given data on the influence of device geometry on sensitivity. Experimental results indicate a linear relationship between output current and magnetic flux density, and an unexplained nonlinear variation of output with device current. Comparison of experimental results with theory indicates a carrier Hall mobility in the channel of 116 cm2/V.s.

P.W. Fry

Papers

A silicon MOS magnetic field transducer of high sensitivity