A photodetecting device that rejects ambient light

• Main Author: Li, Ning
• Other Authors: Allstot, David J.
• Language: en_US
• Published: 2012
• Subjects: Photoelectronic devices > Design and construction
• Online Access: http://hdl.handle.net/1957/34086

The integration of photodetectors with IC circuits provides a significant improvement over conventional designs. Featuring noise reduction, extended frequency responses, lower power consumption, and data operations, these integrated devices open challenging opportunities for many applications. One type of photodetector has the potential for important applications in the life science and remote sensing fields -- a photodetecting device that detects modulated light while rejecting ambient light. A circuit that can reject very bright ambient light yet provide high AC gain for the best signal-to-noise ratio was simulated, constructed and tested by discrete components, and excellent results were obtained. Using 80 klux tungsten light, this device detected an 0.08 lux light signal modulated at 16 kHz, rejecting more than 120 dB of DC light. This circuit was demonstrated by application to a plant physiology study, and the results were also significant. Based on a 1.2 ��m n-well CMOS process, a monolithic device that rejects DC light was designed and simulated by using HSPICE and the SWITCAP2 programs. It was found that a rejection of about 112 dB of DC light may be realized by the CMOS monolithic device. A structure extending this sensor to an imaging device that rejects DC ambient light is also proposed. === Graduation date: 1997