Signal and Noise Analysis of an Open-Circuit Voltage Pixel for Uncooled Infrared Image Sensors

An imaging pixel unit-cell topology leveraging a photodetector in the forward-bias region is proposed. Connecting the anode of the photodiode to the gate of a NMOS device operating in the subthreshold region provides the basis for a new open-circuit voltage pixel (VocP) architecture. Theoretical ana...

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Veröffentlicht in:IEEE transactions on circuits and systems. I, Regular papers Regular papers, 2021-05, Vol.68 (5), p.1827-1840
Hauptverfasser: Fragasse, Roman, Tantawy, Ramy, Smith, Dale, Specht, Teressa, Taghipour, Zahra, Hooser, Phillip V., Taylor, Chris, Ronningen, Theodore J., Fuller, Earl, Reyner, Charles, Duran, Josh, Ariyawansa, Gamini, Krishna, Sanjay, Khalil, Waleed
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Sprache:eng
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Zusammenfassung:An imaging pixel unit-cell topology leveraging a photodetector in the forward-bias region is proposed. Connecting the anode of the photodiode to the gate of a NMOS device operating in the subthreshold region provides the basis for a new open-circuit voltage pixel (VocP) architecture. Theoretical analysis is presented to show the response and performance benefits of the VocP in comparison to a conventional pixel. Based on this analysis, the signal and noise relationships for both pixels are derived and leveraged to construct an end-to-end readout system model. The model results highlight potential performance benefits of the VocP over a conventional direct-injection pixel topology. To verify the analysis, the proposed VocP readout architecture is fabricated along with a conventional direct-injection pixel readout in a 0.18~\mathrm {\mu }\text{m} CMOS technology. The VocP performance is compared to a traditional reverse-bias current-mode photodetector configuration. Simulation, modeling, and measurements align with the proposed analytical model. Benefits in system sensitivity and dynamic range are demonstrated showing more than a 2\times improvement in noise-equivalent temperature difference and a 4 dB improvement in dynamic range.
ISSN:1549-8328
1558-0806
DOI:10.1109/TCSI.2021.3068595