I2C System-on-Chip for bi-dimensional gas-sensor arrays providing extended dynamic-range A/D conversion and row temperature regulation

An I²C programmable 0.35μm CMOS System-on-Chip (SoC) for bi-dimensional gas-sensor arrays providing extended dynamic range read-out with suitable embedded A/D converter and digitally controlled row temperature has been developed. The SoC also features low-power consumption, low-cost production, wide re-configurability and thus large scale compliance with several types of micro-sensors, achieving maximum performance if connected to resistive metal-oxide gas-sensor grids. The CMOS SoC read-out sub-circuit is inspired to laboratory professional electrometers and made up of a current to digital converter plus suitable very low insertion loss analog multiplexers. If connected to a 5×5 gas-sensor array, it features 380 possible measurement configurations. Arbitrary read-out sequences and temperature profiles, in time and in space, in the range [25°C÷500°C] may be run through embedded I²C interface and, without requiring calibration circuits, the SoC features over 160dB measured dynamic range in sensor current read-out with a worst-case output rate of 1 reading per second. Concerning instead digital row temperature regulation, the SoC sub-circuit features an accuracy, including ripple, better than 1°C reaching the set-point temperature value in less than 30ms.