Advancing Uncooled Infrared Imagers Using An Open-Circuit Voltage Pixel

• Published in: 2020 IEEE 11th Latin American Symposium on Circuits & Systems (LASCAS) pp. 1 - 4
• Main Authors: Fragasse, Roman, Tantawy, Ramy, Smith, Shane, Specht, Teressa, Taghipour, Zahra, Van Hooser, Phillip, Taylor, Christopher, Ronningen, Theodore J., Fuller, Earl, Fink, Rudy, Krishna, Sanjay, Khalil, Waleed
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.02.2020
• Subjects: Mid-wave; MWIR; open-circuit voltage; readout; ROIC; V oc
• ISSN: 2473-4667
• DOI: 10.1109/LASCAS45839.2020.9069008

A topology leveraging a photodetector in the forward bias region generating an open-circuit voltage is proposed. Connecting the anode of the photodetector to the gate of a MOSFET device operating in the subthreshold region provides the basis for a new open-circuit voltage pixel (VocP). Theoretical analysis outlining the effective photodetector response and performance benefits is described. An integrated circuit (IC) with direct-injection pixels modified to support the VocP front-end and analog output readout fabricated in a CMOS 0.18 μm technology is also presented. The IC allows testing of mid-wave infrared (IR) photodiodes operating in both the photocurrent and VocP modes. The VocP pixel is compared to a traditional reverse bias current mode photodetector configuration. Simulation, modeling, and measurement show improved sensitivity and faster response time for the VocP over direct photocurrent detection.