2021 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) | 2021
A Versatile Direct-Digital Interface for Resistive Sensors Using Sigma-Delta Approach
Abstract
A sigma-delta principle based linearizing direct-digital converter for giant magnetoresistance sensors was presented in an earlier work. In this paper, the proposed converter circuit is enhanced to interface different resistive-sensor configurations, with minor maneuvering of the existing front-end. The efficacy and versatility of the interface to work with single-element, differential, inverse-type or half-bridge resistive sensor structures are elaborated. The features of the implementation are: i) linear digital output, ii) zero output-offset and positive slope of the transfer characteristic, iii) utilizing the full output-range, iv) use of single reference voltage etc. An extensive simulation study is presented to show the performance of the scheme with different types of sensors, exhibiting very small or highly nonlinear resistance variations. The low non-linearity errors prove the efficacy of the modulator. An uncertainty analysis of the important circuit parameters demonstrate their error contribution to the output.