An Extended Time-Mode Digital Pixel CMOS Image Sensor for IoT Applications.

Area of Science:

• Electrical Engineering
• Sensor Technology
• Integrated Circuits

Background:

• Time-mode digital pixel sensors are crucial for Internet-of-Things (IoT) applications demanding compact, low-power operation in dim environments.
• Existing time-mode sensors face practical limitations in dynamic range due to clock frequency and device leakage, despite theoretical advantages.

Purpose of the Study:

• To propose an extended time-mode digitization technique and a novel low-leakage pixel circuit.
• To enhance the accommodation of a wide range of light intensities using fewer digital bits.

Main Methods:

• Development of an extended time-mode digitization technique.
• Design of a low-leakage pixel circuit.
• Fabrication of a prototype sensor using a 0.18 μm standard CMOS process.

Main Results:

• The prototype sensor successfully accommodates a minimum light intensity of 0.03 lx.
• Achieved a dynamic range figure-of-merit of 1.6.
• Demonstrated a power figure-of-merit of 37 pJ/frame·pixel.

Conclusions:

• The proposed extended time-mode digitization technique and low-leakage pixel circuit effectively address the limitations of current sensors.
• The developed sensor technology is well-suited for IoT applications requiring high dynamic range and low power consumption in varying light conditions.