Linear Range Enhancement Circuit for LVDT based on Bipolar OTA with Relative Error Control

Abstract

This paper proposes a Linear Range Enhancement Circuit for Linear Variable Differential Transformer (L VDT) which was by inverse hyperbolic tangent function implemented by bipolar type OTA. The proposed circuit requires only 2 OpAmps, a bipolar-type OTA and a small number of passive elements. Furthermore, the mathematical models were used in the analysis to determine the configuration methods of the circuit to improve the linearity range enhancement techniques under controlled maximum relative error (%). Two configuration methods of relative error are 0% at center with flat top and ripple top with specific maximum relative error. The Pspice simulation results show the efficiency of the proposed technique for widening the linear operating displacement of the transducer up to 30mm for LVDT (ks = 50 v/m, and kn = 0.2) for 1 % of maximum relative error.