A 0.1% accuracy 100Ω-20MΩ dynamic range integrated gas sensor interface circuit with 13+4 bit digital output

This paper presents the design and the characterization of an integrated wide-range interface circuit for resistive sensors. The device is actually a multi-scale transresistance continuous time amplifier followed by a 13-bit incremental A/D converter. As shown in measurements the worst case resolution is near to 0.1% over a range of 5.3 decades [100Ω-20MΩ] thanks to a calibration technique which cancels offset and gain error mismatch between scales. The chip has been designed in 0.35μm CMOS technology.