Readout integrated circuit for small-sized and low-power gas sensor based on hemt device

Abstract

This paper presents a small-sized, low-power gas sensor system combining a high-elec-tron-mobility transistor (HEMT) device and readout integrated circuit (ROIC). Using a semiconduc-tor-based HEMT as a gas-sensing device, it is possible to secure high sensitivity, reduced complex-ity, low power, and small size of the ROIC sensor system. Unlike existing gas sensors comprising only HEMT elements, the proposed sensor system has both an ROIC and a digital controller and can control sensor operation through a simple calibration process with digital signal processing while maintaining constant performance despite variations. The ROIC mainly consists of a transim-pedance amplifier (TIA), a negative-voltage generator, and an analog-to-digital converter (ADC) and is designed to match a minimum target detection unit of 1 ppm for hydrogen. The prototype ROIC for the HEMT presented herein was implemented in a 0.18 µm complementary metal–oxide– semiconductor (CMOS) process. The total measured power consumption and detection unit of the proposed ROIC for hydrogen gas were 3.1 mW and 2.6 ppm, respectively.