A MOX gas sensors resistance-to-digital CMOS interface with 8-bits resolution and 128dB dynamic range for low-power consumer applications

In this paper an interface circuit for MOX gas sensor is presented. It is based on a resistance-to-frequency converter and improves existing solutions in term of performance (offset) and power efficiency. The resistive range covered is 100Ω-1MΩ, with an equivalent 8-bit precision in a total measurement time of 1 second. This corresponds to a dynamic range of about 128dB. Power consumption and design strategy are optimized for mass production targeting consumer applications. The interface is implemented in a standard CMOS 130nm technology with an area of 125000 μm 2 and 450μA of current consumption.