Title :
Linear–Logarithmic CMOS Pixel With Tunable Dynamic Range
Author :
Vatteroni, Monica ; Valdastri, Pietro ; Sartori, Alvise ; Menciassi, Arianna ; Dario, Paolo
Author_Institution :
BioRobotics Inst., Scuola Superiore Sant´´Anna, Pisa, Italy
fDate :
4/1/2011 12:00:00 AM
Abstract :
A CMOS pixel with linear-logarithmic response and programmable dynamic range (DR), based on a tunable transition point, has purposely been designed for endoscopic applications. A theoretical model of the pixel was developed and validated. A chip with a 100×100 pixel array and a 12-b digital output was fabricated in a 0.35-μm technology and was fully tested, thus demonstrating state-of-the-art performance in terms of DR and noise. Intraframe DR proved to be extendable to more than 110 dB through a logarithmic compression of the signal in the light irradiation power density (LIPD) range. The measured temporal noise (pixel noise) was less than 0.22% over the full range. The architecture presented limited fixed pattern noise (FPN) due to the scheme adopted, which allowed its correction over the full signal range: FPN was 0.83% (1.37%) in the linear (logarithmic) region. Although the test chip was designed mainly for endoscopic applications, the technology may also be applied to other fields, e.g., robotics, security and industrial automation, whenever high DR is a crucial feature.
Keywords :
CMOS image sensors; endoscopes; medical image processing; digital output; endoscopic application; fixed pattern noise; intraframe DR; light irradiation power density range; linear logarithmic CMOS pixel array; linear logarithmic response; logarithmic compression; programmable dynamic range; state-of-the-art performance; temporal noise; test chip; tunable dynamic range; tunable transition point; CMOS integrated circuits; Interactive systems; Internet; Pixel; Transistors; Video recording; Web sites; CMOS imager; endoscopy; logarithmic response; pixel;
Journal_Title :
Electron Devices, IEEE Transactions on
DOI :
10.1109/TED.2011.2106787