A High Dynamic Range CMOS Interface for Resistive Gas Sensor Array with Gradient Temperature Control

A complete front-end system for resistive gas sensor array is presented. The interface is composed by 8 read-out channels and by 2 closed-loop temperature control circuits. The IC gas sensor read-out structure is based on a controlled oscillator, which acts like a resistance-to-period converter, and achieves a 0.5%-linearity over 500 kOmega-1 GOmega sensor resistance range with a SNR better than 48 dB, corresponding to 114 dB-DR. The temperature control systems allows maintaining a 100degC gradient on the array of sensor, selected in the temperature range 100degC-400degC, with a plusmn2.5degC accuracy. The full device is designed in a standard 0.35 mum CMOS technology. The die area is 1.8 mm² with a total power consumption of 27 mW from a single 3.3 V supply voltage