Three-Electrode Metal-Oxide Gas Sensor System With CMOS Interface IC

This paper proposes a system with CMOS interface IC for three-electrode metal-oxide gas sensor. The proposed system adopts a switching scheme using pulsewidth modulation signals in order to control the temperature of the heater and measure the resistance of the sensor simultaneously in actual. Furthermore, the switching method can solve the electrical asymmetry issue of the sensor. Wide variation in the resistance of the sensor is covered by the mode-adjustable integrator. The proposed system achieves temperature control up to 250 °C, and detectable resistance range of the sensing material from 80 Ω to 2 MQ with relative error of less than 1.5%.