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Journal of Electronic Imaging

Dark current in an active pixel complementary metal-oxide-semiconductor sensor
Author(s): Justin Dunlap; William C. Porter; Erik Bodegom; Ralf Widenhorn
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Paper Abstract

We present an analysis of dark current from a complementary metal-oxide-semiconductor (CMOS) active pixels sensor with global shutter. The presence of two sources of dark current, one within the collection area of the pixel and another within the sense node, present complications to correction of the dark current. The two sources are shown to generate unique and characteristic dark current behavior with respect to varying exposure time, temperature, and/or frame rate. In particular, a pixel with storage time in the sense node will show a dark current dependence on frame rate and the appearance of being a "stuck pixel" with values independent of exposure time. On the other hand, a pixel with an impurity located within the collection area will show no frame rate dependence, but rather a linear dependence on exposure time. A method of computing dark frames based on past dark current behavior of the sensor is presented and shown to intrinsically compensate for the two different and unique sources. In addition, dark frames requiring subtraction of negative values, arising from the option to modify the bias offset, are shown to be appropriate and possible using the computational method.

Paper Details

Date Published: 1 January 2011
PDF: 8 pages
J. Electron. Imag. 20(1) 013005 doi: 10.1117/1.3533328
Published in: Journal of Electronic Imaging Volume 20, Issue 1
Show Author Affiliations
Justin Dunlap, Portland State Univ. (United States)
William C. Porter, Portland State Univ. (United States)
Erik Bodegom, Portland State Univ. (United States)
Ralf Widenhorn, Portland State Univ. (United States)

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