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Low-Power Organic Light Sensor Array Based on Active-Matrix Common-Gate Transimpedance Amplifier on Foil for Imaging Applications

: Elsaegh, S.; Veit, C.; Zschieschang, U.; Amayreh, M.; Letzkus, F.; Sailer, H.; Jurisch, M.; Burghartz, J.; Würfel, U.; Klauk, H.; Zappe, H.; Manoli, Y.


IEEE journal of solid-state circuits 55 (2020), Nr.9, S.2553-2566
ISSN: 0018-9200
Fraunhofer ISE ()
Photovoltaik; organic imaging; organic light sensor; organic photodetector (OPD); organic thin-film transistors (TFTs); transimpedance amplifier (TIA); Neuartige Photovoltaik-Technologien

This article presents a 57.6-μW mechanically flexible active-matrix imaging system based on a 4x 5 array of light sensors, each composed of a photodetector (PD) using a light-sensitive organic polymer and a transimpedance amplifier (TIA) based on organic thin-film transistors and integrated thin-film carbon resistors. The PDs and the electronics are fabricated on separate plastic films and integrated into a system. Two different topologies for the TIA are designed, implemented, and characterized. The first topology is a self-biased TIA based on a gain-boosted operational amplifier (op-amp), providing an open-loop dc gain of 41.3 dB. This op-amp-based TIA, with a feedback resistor, provides stable current-to-voltage conversion (0-100 μA and 2.0-3.7 V) at frequencies up to 300 Hz. The second topology is a low-power gain-boosted common-gate (GB CG) TIA that performs current-to-voltage conversion with a nonlinearity as small as ±0.3% within a bandwidth of 1 kHz. The output voltages of the light sensors are read and converted into a 4x 5 pixel gray-scale image displayed on a computer monitor to visualize the functionality of the system.