CMOS self-powered monolithic light-direction sensor with digitalized output.

Area of Science:

• Photonics
• Integrated Circuit Design
• Sensor Technology

Background:

• Accurate detection of incident light direction is crucial for various applications.
• Existing methods often require external power, complex optical setups, or mechanical components.
• A self-powered, integrated solution for light-angle detection is highly desirable.

Purpose of the Study:

• To present a novel self-powered chip for detecting the direction of incident light.
• To achieve direct digitized output without off-chip power or external components.
• To demonstrate a compact and efficient light-angle sensing solution.

Main Methods:

• Implementation of a chip in a standard 0.5 μm CMOS process.
• Fabrication of a microscale metal baffle using stacked metal layers for on-chip shadowing.
• Utilizing N-well/p+ photodiode arrays on either side of the baffle to sense light.
• Employing a current mirror circuit to compare photocurrents and generate a digital signal indicating light angle.

Main Results:

• The chip directly provides digitized output, requiring no off-chip power supply.
• The sensor achieved a maximum error of only 2 degrees over a 110-degree test range.
• Photocurrent generation is modulated by photodiode size and shadowing, which is dependent on incident light angle.

Conclusions:

• The developed self-powered chip offers a highly accurate and integrated solution for light-direction detection.
• This technology eliminates the need for external power and optical/mechanical components, simplifying system design.
• The sensor demonstrates significant potential for applications requiring precise, autonomous light-angle sensing.