TFT active image sensor with current-mode readout circuit for digital x-ray fluoroscopy

Nader Safavian; G. R. Chaji; A. Nathan; J. A. Rowlands

doi:10.1117/12.629811

13 October 2005 TFT active image sensor with current-mode readout circuit for digital x-ray fluoroscopy

Nader Safavian, G. R. Chaji, A. Nathan, J. A. Rowlands

Proceedings Volume 5969, Photonic Applications in Biosensing and Imaging; 596929 (2005) https://doi.org/10.1117/12.629811
Event: Photonics North, 2005, Toronto, Canada

Abstract

In this paper, an innovative current-programmed, current-output active TFT image sensor suitable for real time x-ray imaging (fluoroscopy) using hydrogenated amorphous silicon (a-Si:H) thin film transistor (TFT) technology coupled with a transimpedance feedback column amplifier for pixel signal readout is presented. Simulation results show that this new TFT circuit can successfully compensate for variations in a-Si:H TFT characteristics under prolonged gate voltage stress. The readout is fast enough to fulfill the timing requirements of digital fluoroscopy. Dynamic effects such as charge injection, charge feed-through and drain-source voltage variation as well as additive noise of the pixel TFTs induce error on the output current of the pixel. To explore the dependence of this error on pixel parameters, concise analytical expressions are derived which can be used to reduce the amount of the output current error by proper pixel design.

Citation Download Citation

Nader Safavian, G. R. Chaji, A. Nathan, and J. A. Rowlands "TFT active image sensor with current-mode readout circuit for digital x-ray fluoroscopy", Proc. SPIE 5969, Photonic Applications in Biosensing and Imaging, 596929 (13 October 2005); https://doi.org/10.1117/12.629811

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