Low-Power Organic Light Sensor Array Based on Active-Matrix Common-Gate Transimpedance Amplifier on Foil for Imaging Applications
Samar Elsaegh, Clemens Veit, Ute Zschieschang, Mohammad Amayreh, Florian Letzkus, Holger Sailer, Michael Jurisch, Joachim N. Burghartz, Uli Würfel, Hagen Klauk, Hans Zappe, Yiannos Manoli
Abstract
This article presents a 57.6-μW mechanically flexible active-matrix imaging system based on a 4 × 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 4 × 5 pixel gray-scale image displayed on a computer monitor to visualize the functionality of the system.