Design and Reliability Analysis of Differential Resistance to Current Conversion Circuit for Biomedical Application of Gas Sensing

Abstract

Gas sensing in biomedical applications shows a conversion of the concentration of the exhaled gas to a variation in resistance, so an electronic integrated interface circuit is required to analyse the exhaled gases, which are indications for many diseases. In this paper, a resistance to current conversion circuit based on differential biasing for Electronic nose (E-nose) breath analyser is presented. Over more than 5-decades (500Ω to 100MΩ) input resistance range, a precision, less than 1%, required by novel gas sensing system in portable applications, is preserved. Therefore, the proposed circuit obtains high accuracy under simulation. The outputs of the proposed Resistance to Current (R-to-I) conversion circuit achieve a percentage error below 0.25% under environment corners. The reliability of the proposed circuit is also investigated under the effect of process variations. In order to assess the correctness of the proposed architecture, the circuit was compared to similar solutions presented in literature where the proposed architecture attains a worst-case percentage error of 0.05%.