A Fully Integrated Gas Detection System With Programmable Heating Voltage and Digital Output Rate for Gas Sensor Array

Abstract

In this paper, a gas detection system for $2\times 2$ MEMS gas sensor array is proposed. It has multiple measurement channels, programmable heating voltage, programmable measurement time, 24-bit digital output with 8-bit accuracy, wide measurement range and high linearity. The chip is realized in SMIC 180 nm complementary metal oxide semiconductor technology with an area of 1.58 mm $\times1.66$ mm. The result of the fixed resistance measurement shows that the linearity of the resistance ranges ( $200~\Omega $ -200 $\text{K}\Omega $ , $200~\Omega $ -500 $\text{K}\Omega $ , $200~\Omega $ -1 $\text{M}\Omega $ , $200~\Omega $ -2 $\text{M}\Omega $ , $200~\Omega $ -5M $\Omega $ , and $200~\Omega $ -10M $\Omega$ ) are all less than 1% at different measurement time intervals. At 1 s measurement time, the circuit has a wide detectable resistance range ( $200~\Omega $ -10 $\text{M}\Omega$ ), and high linearity of 0.3047%. The experimental results combined with the resistive MEMS gas sensor array show that the circuit has a good detection effect in the gas concentration range (0 ppm-340 ppm), and can even detect the change of gas concentration at a low concentration of 0.1 ppm. Moreover, the system can detect different responses of the same sensor at different heating voltages.