An efficient signal conditioning (SC) scheme that helps to obtain a linear output from a magnetoresistive (MR) angle sensor for 0\circ-360 \circ range is presented in this paper. Most of the existing MR angle sensors have a sine/cosine relationship between the output and sensing angle, but a linear characteristic will be very useful. The new SC circuit of the proposed transducer accepts and processes output signals from an MR sensor that is sine/cosine in nature and gives an output directly proportional to the sensing angle. The sensitivity of the transducer output to variations in different circuit and mechanical parameters has been analyzed in detail, and their effect has been quantified. The functionality of the SC has been studied using SPICE simulations. A prototype of the proposed SC circuit has been built and tested using emulated sensor output signals. The output of the prototype circuit was linear from 0\circ to 360 \circ, and worst case error was less than 0.08%. An angle sensor unit has been built using an MR sensor IC, interfaced to the SC circuit and tested. As expected, the output was found to be linear for a full-circle range. © 1963-2012 IEEE.

Boby George

Department of Electrical Engineering

ANGLE TRANSDUCER

Giant magnetoresistances (GMR)

LINEAR CHARACTERISTICS

MECHANICAL PARAMETERS

Precision measurement

Prototype circuits

SPICE SIMULATIONS

Tunneling magnetoresistance

Giant magnetoresistance

Hall effect

Magnetic recording

Sensitivity analysis

Sensors

Signal conditioning circuits

strain measurement

transducers

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IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

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IIT Madras

New Signal Conditioning Circuit for MR Angle Transducers With Full-Circle Range

IEEE Transactions on Instrumentation and Measurement

This chapter presents a brief overview of some of the widely used magnetic field sensors, with an emphasis on commercially available solid-state sensors such as Hall effect and magnetoresistive sensors. In addition to this, the chapter presents some of the industrial applications of these sensors and the associated interfacing circuits required to obtain a usable electrical output from them. The chapter concludes with the design specifics and evaluation of a through-shaft angle sensor that employs a combination of variable reluctance technique and Hall sensor. © 2018 Elsevier Ltd All rights reserved.

Smart Sensors and MEMS: Intelligent Sensing Devices and Microsystems for Industrial Applications: Second Edition

Magnetic sensors and industrial sensing applications

A new, simple and efficient electronic scheme suitable for magneto-resistive angle sensors with 0-360 range is presented in this paper. Most of the existing magneto-resistive angle sensors have a sine/cosine relationship between the output and sensing angle but a linear characteristic is highly useful. The proposed Signal Conditioning (SC) method accepts and processes output signal from the sensor that is sine/cosine in-nature and provides an output directly proportional to the sensing angle. Accuracy of the final output depends mainly on a dc reference voltage and a reference sinusoidal signal. A prototype of the proposed SC circuit has been built and tested to verify the practicality of the scheme. Output of the prototype circuit was linear across 0 to 360 and worst-case error was less than 0.08%. An angle sensor assembly using a magneto-resistive sensing element has been built for further tests. This unit provides two output signals. The SC circuit is an optimized scheme for best accuracy when operating with these signals. The sensor unit has been interfaced with the SC circuit and tested. As expected, the output was found to be linear for the full-circle range. © 2012 IEEE.

2012 IEEE I2MTC - International Instrumentation and Measurement Technology Conference, Proceedings

A novel signal conditioning scheme for magneto-resistive angle sensors

A new Tunneling Magneto-Resistance (TMR) based angle transducer realized with a novel Signal Conditioning (SC) scheme that accepts TMR angle sensing elements possessing sine/cosine output characteristics and provides a final output that changes linearly with the angle being sensed over a full-circle range (0-360°) is presented in this paper. The proposed scheme converts the angle being sensed by the TMR sensing elements into an equivalent phase shift of a sinusoid, whose amplitude is dictated by the flux produced by the permanent magnet employed in the transducer. The phase of the sinusoid is then converted as an output voltage that is dependent only on the phase angle and not on the magnetic strength. Thus even over a long period, over which the strength of the permanent magnet may decay, the accuracy of angle sensing is preserved. A prototype angle sensor, using a TMR IC, and proposed SC circuit has been built and tested. The output of the transducer was found to be linear across the entire 0-360°. The worst-case error observed for the transducer was less than ±0.85 % of the full-scale while that for the SC unit alone was less than ±0.1 %. © 2012 IEEE.

A linear Tunneling Magneto-Resistance angle transducer

This paper presents a new, simple but effective, electronic method to obtain inverse-cosine of an electrical variable. The proposed method is very useful for linearization of sensors whose output is a cosine or sine function of the physical quantity being sensed. The inverse-cosine of the variable is obtained by comparing it with a reference sinusoidal wave. The proposed method is easy to implement using electronic components. Using the new technique, a giant magneto-resistance-based angle sensor that provides an output linearly proportional to the angle being sensed has been developed, and the details are reported in this paper. A prototype of the angle sensor has been built, and the practicality of the new method has been tested successfully. The developed sensor provides a linear output for a range of 0° to 180°. The worst case error was found to be less than 0.35° for a range of 10°-170°. © 2012 IEEE.

Electronic scheme for computing inverse-cosine and its application to a GMR based angle sensor

A linear variable differential capacitive transducer for the measurement of planar angles (from 0° to 360°) is presented in this paper. The sensor part of the transducer is made of parallel plates of standard and easy-to-fabricate shapes, and the signal-conditioning electronics are realized, employing a couple of simple relaxation oscillators. The output of the transducer is only dictated by a pair of dc reference voltages, and hence, high accuracy and linearity over the entire range (from 0° to 360° are easily obtained by the use of precision dc reference voltages. Detailed analysis indicates that the sensitivity of the transducer is minimal for variations in different parameters. Experimental results obtained on a prototype transducer that has been built and tested establish the efficacy of the proposed transducer. The worst-case error of the prototype transducer is found to be less than 0.1%. © 2008 IEEE.

A linear variable differential capacitive transducer for sensing planar angles

i-manager's Journal on Circuits and Systems

TRENDS IN ESD PROTECTION DESIGN FOR I/O LIBRARIES IN ADVANCED CMOS AND FINFET TECHNOLOGIES

New signal conditioning circuit for MR angle transducers with full-circle range

Journal	IEEE Transactions on Instrumentation and Measurement
ISSN	00189456
Open Access	No