125ppm resolution and 120dB dynamic range nanoparticle chemiresistor array readout circuit

Nanoparticle coated chemiresistor (CR) arrays enable highly sensitive vapor detection in systems such as a micro gas chromatograph or an electronic nose. However, they suffer shortcomings such as a small response compared to a large baseline value, large baseline variation across devices, and significant baseline drift over time. This paper describes a new high-resolution CR array readout circuit with adaptive baseline control. The 8-channel readout circuit occupies 2.2mm × 2.2mm in 0.5μm CMOS technology, consuming 66μW per channel from a 3.3V power supply. It achieves a worst-case resolution of 125ppm over a baseline resistance of 60kΩ to 10MΩ, equivalent to 120dB dynamic range.