Reconfigurable integrated wide-dynamic-range read-out circuit for MOX gas-sensor grids providing local temperature regulation

A reconfigurable, low-cost, wide-dynamic-range, 0.35μm CMOS read-out ASIC for resistive bi-dimensional Metal-Oxide gas-sensor grids, providing local temperature regulation, has been developed. The MOX grid read-out circuit is based on a resistance to digital converter plus suitable low insertion loss analog multiplexers, delivering up to 380 possible measurement configurations for a 5×5 sensing device. Desired grid read-out sequences and temperature profiles, in time and in space, within the range [25°C÷500°C], may be executed by simply loading suitable configuration data onto embedded slave I²C registers. Without the aid of bulky calibration circuits the ASIC features 167dB dynamic range for sensor resistance value read-out with a guaranteed output rate of 1Hz, and an estimated accuracy, including ripple, better than 1°C in each sensor row temperature regulation, while actuating the maximum temperature set-point transient in less than 30ms.