An Analog Adaptive Reference Generation Readout Integrated Circuit for Baseline-Free Gas Sensor Measurements

The distribution of baselines in gas sensors poses a challenge in the readout integrated circuit (ROIC) design and can lead to reduced signal accuracy. In this study, we introduce a straightforward yet effective ROIC structure tailored to address baseline variations in gas sensors. The proposed ROIC incorporates an analog adaptive reference generation scheme, which directly samples the reference voltage from the gas sensor, using it as the baseline for accurate signal extraction. This approach enables the efficient extraction of the gas sensor's output signal by correlating it with the baseline. Furthermore, extending the adaptive referencing cycles can alleviate the design complexity imposed by high-performance requirements of ADC, leading to an overall performance enhancement that remains competitive. The prototype ROIC was fabricated using a 180-nm standard CMOS process, exhibiting a total power consumption of about 300 μ W at a conversion rate of 1 kSPS. An integrated noise, measured within 1 Hz-5 kHz range, was 133.21 nVrms, resulting in a dynamic range (DR) of 150 dB. The proposed ROIC achieved a competitive figure of merit (FoM) of 127 dB. To validate the potential and commercial viability of the prototype ROIC, assessments were conducted at both the printed circuit board (PCB) and silicon chip levels in this work.