A Wide Linearity Range of LVDT Using Approximate Function

This paper introduces linearity operation range extension of LVDT based on analog signal conditioning technique by using the approximate function of inverse hyperbolic tangent without modification of LVDT structure. The designed circuit comprises inexpensive commercial devices and it is simplicity. It consists of op-amps, diodes, and resistors. The sub-circuits in this proposed circuit are only logarithmic and summing amplifiers. The simulation results of the proposed system by using PSpice show that this proposed circuit can extend the original linearity range of LVDT from ±2mm to the linearity operation range of ±15mm which means it can extend the linearity range operation of LVDT approximately 7.5 times of the original linearity range of LVDT from demodulated signal process.