Above 160 dB dynamic-range gas-sensor-grid front-end integrated circuit with 500 °C, 1.5°C/pitch temperature gradient synthesis, 20-channel MUX, and I2C interface

Abstract

A low-cost, reconfigurable integrated read-out circuit optimized for bi-dimensional arrays of metal-oxide (MOX) gas-sensors has been developed. The self-consistent ASIC for gas-sensor array interfacing, including temperature synthesis, has been fabricated in a 0.35 μm CMOS technology with 3.3 V supply and characterized. The device provides a measured read-out dynamic range of 162 dB and effective independent row temperature regulation of 1.5°C within the range [25°C ÷ 500°C]. The ASIC can be completely configured and read-out through an embedded I2C interface. The gas-sensor read-out circuit consists of a resistance to digital converter and an intrinsic very low insertion loss 20-channel analog multiplexer, while the temperature regulation circuit consists of five closed-loop independent modules reading and driving their associated thermometers and heating actuators respectively, with the aim of reaching the assigned set-point temperature values in less than 50 ms with maximum 1 °C peak residual ripple.