Metal Oxide Gas Sensor Electronic Interfaces

In this chapter, we introduce Metal-Oxide (MOX) based semiconductor gas sensors as good candidates for realizing a gas sensing system due to their variety of advantages such as low cost, long life time, high sensitivity, small size, simplicity of operation, flexibility in production, and compatibility with the standard CMOS process. A review of MOX gas sensors (commercial and noncommercial) is presented to draw the main requirements for the electronic interface circuit design. The chapter presents a review of the state‐of‐the‐art for possible circuit interfaces provided in literature. Electronic interface circuits based on time/frequency are preferable when converting wide resistance range with high linearity (low linearity error) without any need of calibration since the output periodic waveform can be easily converted to digital domain. A detailed explanation for each building block constituting R‐to‐T architecture is provided highlighting the main requirements to achieve high linearity and wide dynamic range (DR).