At the Electronic Imaging conference a great paper was presented this morning (in the session on digital photography), talking about a new type of image sensor. A high-speed imager was introduced by people from Tohoku University, Japan, paper was entitled : “A prototype high-speed CMOS image sensor with 10,000,000 burst-frame rate and 10,000 continuous-frame rate”. Presentation was done by Yasuhisa Tochigi.
Basically it is a CMOS imager with a 4T pixel including a LOFIC capacitor for high dynamic range (not surprising to see a LOFIC here, because the co-authors of the paper worked on LOFIC in cooperation with TI Japan). In total the sensor has 72 H x 32 V pixels. Remarkable is to find the current source of the source follower in the pixel itself. This has to do with the speed and voltage losses in resistive column busses.
In the column circuitry, every column has 104 analog memories/pixel. So every column has 104 x 32 capacitors included. Capacitors are made as a stacked combination of a MOS transistor and a PIP capacitor. The 104 analog capacitors per pixel are used to store the information of maximum 52 images in burst mode. Every pixel signal can be sampled (and stored) twice to measure the reset reference level and the signal level. So CDS is possible ! Without CDS, the capacitor bank can store 103 images, apparently 1 capacitor is needed to store the offset of the pixel.
To maintain the speed, every pixel has its own column bus, so a complete set of 32 column lines is coming from the pixel array into the column circuitry. Very impressive !
Some numbers : pixel size : 48 x 48 mm2, fill factor : 35 %, 0.18 mm technology with 2P3M, 60 mV/e–, 5 e– input-referred noise (speed ?), dissipation : 1W @ 100 kpixels.
The presentation was concluded with some nice demonstrations of the high-speed mode of the sensor, both in burst and in continuous mode. Great piece of work, very nice presentation. Congratulations !
Albert, 25-01-2011
Hi Albert,
The papers from the conference are already in the SPIE digital library:
http://spiedigitallibrary.org/proceedings/resource/2/psisdg/7876/1?isAuthorized=no
For this particular one the noise and power numbers are not mentioned in the paper. However, the only noise measurement they show (which does not give any actual information) is done in “burst” mode, which is their 10 Mfps mode.
Regards,
David