"CMOS technology brings new opportunities for consumer imaging." Photonics
Spectra Dec 2005 pp 60-62
Here is a poorly written article from Kodak (marketing?) on CMOS sensor
development directions. Despite the poor writing there is some interesting
information. Claimed new is stuff (some similar to previously described by
Foveon and others) combining semi-adjacent pixels either for making greatly
improved ASA sensitivity or for B&W or for video/still combined camera use.
There are some impressive curves showing how big an improvement is possible
using the described techniques.
Improved architecture but still reducing the per pixel transistor count to
~1.75 by sharing transitor structures between adjacent pixels despite a higher
transistor count of the actual blocks used. Many companies do this sharing to
some degree, so transistors/pixel is an interesting metric especially if
combined with more complex blocks used. The lowered count is always helpful as
it allows increased on chip functionality by freeing space or more importantly
for improved fill factor (reduces noise,wide angle lens sensitivity etc).
Claims dark current (noise) reduction of ~5X.
Some of the claimed new things (eg pinned photo-diodes) sound similar to what
others have been doing for a while, so maybe they are only new to Kodak,and it
is part of the marketing hype of the article. I think Kodak bought the rights
to some of the lower resolution Foveon technology (from Polaroid), so maybe
some of the adjacent pixel stuff just reflects that ip. Maybe they will buy out
Foveon or license more from Foveon given Foveon's lack of heavy duty partner.
Foveon has CMOS ip outside of just the improved anti-aliasing vertical
structure for color filtering.
There is an immense patent base for imaging sensors, so a lot of defensive
cross licensing must be taking place behind the scenes between all these
companies.
Tim Hughes
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