Integrated CMOS interfaces for wide-range resistive gas sensors

In this work, we present novel integrated interfaces for resistive gas sensors. The proposed interfaces, which convert the resistive value into a period (or frequency), have the peculiarity to be able to reveal about six decades of resistive sensor variation, from 10 kΩ up to 10 GΩ, showing high linearity and reduced percentage error between measured and theoretical results. Implemented both in CMOS and with discrete elements, they have been applied with success as carbon nanotubes gas sensor interfaces.