A Linearizing Digitizer for Differential Sensors With Polynomial Characteristics

This paper presents a new linearizing digital converter (LDC) that accepts output from differential type sensors with third-order polynomial transfer characteristics and provides a linear digital output proportional to the measurand. The LDC is realized using a modified dual-slope converter. Detailed operation of the proposed LDC, design procedure, and analysis of the effect of various circuit parameters on performance of the LDC are presented in this paper. The proposed methodology of LDC is also extended for sensors with second-order polynomial characteristics. The functionality of the LDC has been verified with the help of simulation studies. A prototype LDC has been developed and interfaced with a novel reluctance-Hall effect-based angle sensor (having a third-order characteristic) and tested. Test results show that the output of the overall transducer is linear across a wide range of angles, and thus underline the efficacy of the proposed scheme for differential type sensors with third-order transfer characteristics.