Readout Integrated Circuit for Small-Sized and Low-Power Gas Sensor Based on HEMT Device

Area of Science:

• Semiconductor device physics
• Integrated circuit design
• Gas sensing technology

Background:

• Existing gas sensors often lack sensitivity, compactness, and low power consumption.
• High-electron-mobility transistors (HEMTs) offer potential for sensitive gas detection but require integrated readout circuitry.
• Digital control and signal processing are crucial for stable sensor performance amidst environmental variations.

Purpose of the Study:

• To develop a small-sized, low-power gas sensor system integrating a HEMT device with a readout integrated circuit (ROIC).
• To achieve high sensitivity and stable performance for hydrogen gas detection.
• To enable simple calibration and digital control for the sensor system.

Main Methods:

• Utilized a semiconductor-based high-electron-mobility transistor (HEMT) as the core gas-sensing element.
• Designed and implemented a readout integrated circuit (ROIC) comprising a transimpedance amplifier (TIA), negative-voltage generator, and analog-to-digital converter (ADC).
• Integrated the ROIC with a digital controller for sensor operation and signal processing using a 0.18 µm CMOS process.

Main Results:

• The integrated system demonstrated high sensitivity and reduced complexity.
• The prototype ROIC achieved a measured power consumption of 3.1 mW.
• The system's detection unit for hydrogen gas was measured at 2.6 ppm, meeting the target of 1 ppm.

Conclusions:

• The proposed HEMT-based gas sensor system with an integrated ROIC offers a promising solution for low-power, high-sensitivity gas detection.
• The digital controller ensures stable performance and simplifies calibration, overcoming limitations of HEMT-only sensors.
• The successful implementation in a standard CMOS process paves the way for practical, miniaturized gas sensing applications.