A novel signal conditioning scheme for magneto-resistive angle sensors

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.