A 0.85%-precision, 6-decade-range, I2C — Programmable front-end ASIC for resistive gas-sensor arrays with 20-input analog mux, digital output, and 1.5°C-accuracy dynamic temperature synthesis

In this paper a 0.35μm CMOS complete gas-sensor array front-end circuit is presented. The device provides measured read-out dynamic range of 162dB and effective independent row temperature regulation of 1.5°C within the range [25°C-500°C]. The overall system features a power consumption of 2mW/sensor and may be completely configured and read-out thanks to an embedded I²C bus interface, thus allowing the synthesis of ad-hoc sensor grid temperature gradient profiles over time and space through digital setpoint bitstream. Massive compliance with heterogeneous gas microsensors types is guaranteed, achieving maximum performance when connected to chemo-resistive metal-oxide gas-sensor arrays. The read-out circuit consists of a current to digital converter and an intrinsic series lossless insertion 20-channel multiplexer, while temperature regulation circuit is made up of five closed loop independent modules reading and driving their associated thermometers and heating actuators, respectively, reaching the setpoint temperature in less than 30ms.