Title :
A novel hybrid active-passive pixel with correlated double sampling CMOS readout circuit for medical x-ray imaging
Author :
Safavian, N. ; Chaji, G.R. ; Karim, K.S. ; Rowlands, J.A.
Author_Institution :
Electr. & Comput. Eng. Dept., Univ. of Waterloo, Toronto, ON
Abstract :
This paper presents a new hybrid current-programmed, current-output active pixel sensor (APS) suitable for real time X-ray imaging (fluoroscopy) and an off-panel CMOS readout circuit. The pixel circuit is designed using hydrogenated amorphous silicon (a-Si:H) thin film transistor (TFT) technology. The simulation results based on the measured characteristics of a- Si:H TFTs show that the proposed pixel circuit can successfully compensate for characteristic variations (e.g. mobility and threshold voltage shift) in a-Si:H TFTs under prolonged gate voltage stress. The readout circuit exploits correlated double sampling (CDS) technique to reduce the offset current, low frequency noise and fixed-pattern noise (FPN) on the array operation.
Keywords :
CMOS image sensors; diagnostic radiography; image resolution; image sampling; medical image processing; readout electronics; TFT; correlated double sampling CMOS readout circuit; current-output active pixel sensor; fixed-pattern noise; fluoroscopy; hybrid active-passive pixel; hydrogenated amorphous silicon; medical X-ray imaging; thin film transistor; Biomedical imaging; CMOS image sensors; Circuits; Low-frequency noise; Pixel; Sampling methods; Sensor phenomena and characterization; Thin film transistors; Threshold voltage; X-ray imaging;
Conference_Titel :
Circuits and Systems, 2008. ISCAS 2008. IEEE International Symposium on
Conference_Location :
Seattle, WA
Print_ISBN :
978-1-4244-1683-7
Electronic_ISBN :
978-1-4244-1684-4
DOI :
10.1109/ISCAS.2008.4542131
