Evaluation of Simple Linearizing Circuit Topologies for LVDT

This research suggests low-cost and low-complexity lineari-zing interface schemes that are suitable for the enhancement of linearity and range of practical linear variable differential transformers (LVDTs). The simplest proposed scheme uses a circuit made of a few opamps, a multiplier, and some passive components. It is designed to process the second-order-based transfer curve that LVDT obeys for shorter stroke spans and provides a linear output characteristic. Further, an extended linearizer design capable of linearizing the LVDT response to near its full-stroke span is presented. Both designs are simple and can be realized using readily available components. In addition, the proposed schemes provide a positive sensitivity factor, which can be easily tuned. The efficacy of the schemes was evaluated using simulation and experimental studies. Studies show that the developed schemes can give significant improvement in linearity for a span of 72 mm, thereby extending the effective usable range of the LVDT. The worst-case values of nonlinearity error and signal-to-noise ratio observed during experimentation are 0.554% and 103 dB, respectively.