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.