A Self-Powered Gas Sensor Integrated Circuit Based on Photovoltaic Energy Harvesting

Abstract

A self-powered gas sensor integrated circuit (IC) suitable for wireless sensor nodes is designed in 0.18 μm CMOS process. The novel idea of using the output of the photovoltaic (PV) cell covered by the gas-sensing film allows the proposed sensor system to have low power consumption and compact size. A dual-input shared-inductor boost converter is used to harvest energy efficiently from two PV cells instead of connecting these cells in parallel when the system is exposed to gases. This shows up to 11% improvement of conversion efficiency at 2% H2 gas concentration. Maximum end-to-end efficiency of 88% is achieved at an output power of 3 mW, and the quiescent current is only 289 nA. An input-offset-storage autozeroing technique is used for opamp offset cancellation to achieve high-accuracy gas detection. A modified split-capacitor digital-to-analog converter (DAC) architecture is used for achieving a small area in the signal-processing block.