An Interfacing Circuit for Differential Measurement of Chalcogenide-Based Resistive Gas Sensors

We present a differential interface circuit to bias and read chalcogenide-based resistive gas sensors. The topology of the circuit is discussed and simulated using a commercial CMOS technology of 180 nm. The main advantages of the proposed circuit are: low power consumption, wide range of input sensing resistors and its possibility to operate under non-controlled ambient temperature. Results show that the circuit is capable of reading sensing resistances within a range between 2.4 MΩ and 100 MΩ with a measurement uncertainty of 1%. The noise of the circuit was found to be the limiting factor of the measurement accuracy. In the case of a sensing resistance of 50 MΩ (close to the middle of the operating range) the measurement uncertainty is below 0.05 %.