Self-balancing digitizer for resistive half-bridge
Vishal Kumar Jain, Boby George · 2018
This paper presents a self-balancing digitization approach for the resistive sensor interfaced through the half-bridge configuration. The output of the interface circuit is linear and quasi-digital or digital in nature. The scheme is designed such that its output is independent of the variations in the bridge excitation voltage and lead wire resistance. The proposed scheme can be used for resistive sensors with small or large change compared to the nominal resistance, and the full range of the digitizer can be utilized to represent the measurand by simply setting appropriate values for two components in the digitizer. The approach presented does not require a multiplier, compared to the existing methods, and hence the accuracy of the output is not limited due to the non-idealities and limitations of the multiplier. The workability of the proposed circuit is verified in the laboratory with the help of a prototype developed. The maximum non-linearity error that occurred in measured output of the prototype, when tested using a standard resistance box, was less than 0.3% of the full scale. Rise time of the prototype has been measured as 3.6 ms.