A complete front-end system read-out and temperature control for resistive gas sensor array

A complete front-end system for resistive gas sensor array is presented. The system is composed by a substrate temperature control circuit and by a read-out circuit. The temperature control allows maintaining a 100°C temperature gradient selected in the temperature range [150°C-350°C] on the array of sensor. The gas sensor read-out circuit, which acts like a resistance-to-period converter, is suitable to be interfaced to a microcontroller in order to achieve a resolution error lower than 0.5% for a resistance ranging in (300kΩ-300MΩ]. The full device, including 8 read-out channels and 2 temperature control systems, is designed in a standard 0.35μm CMOS technology. The die area is 1.8mm² with a total power consumption of 30mW from a single 3.3V supply voltage.