An Analog Linearizing Circuit for TMR Angle Sensor with Flexible Measurement Range

In this paper, an Analog Linearizing Circuit (ALC) is presented for Tunneling Magneto-Resistance (TMR) angle sensor. The ALC is designed to fetch a linear analog output from sine-cosine natured TMR sensor. The ALC utilizes a quadratureoscillator (QO) to excite the sensor. The ALC output is minimally affected by the phase-imbalance between the excitation signals and the parasitic capacitances of the TMR sensor. The linearizing circuit part of the ALC is designed for the applications that require 360° measurement range. However, a simplified equivalent, suitable for applications with 180° range, is also proposed. The ALC performance is evaluated in simulation studies for several values of QO phase-imbalance. The final output is minimally affected by the QO phase-imbalance. Later, additional simulation tests are carried out with the help of AAT003-10E TMR angle sensor-based evaluation kit. The ALC output non-linearity, in this case, lies close to the inherent non-linearity of the angle sensing kit.