Title :
Low-Noise In-Pixel Comparing Active Pixel Sensor Using Column-Level Single-Slope ADC
Author :
Lee, Dongmyung ; Cho, Kunhee ; Kim, Dongsoo ; Han, Gunhee
Author_Institution :
Dept. of Electr. & Electron. Eng., Yonsei Univ., Seoul
Abstract :
A conventional active pixel sensor (APS) uses a source follower (SF) in a pixel as a buffer. This SF is one of the major causes of nonlinearity, sensitivity degradation, and pixel readout noise. The proposed in-pixel comparing APS uses pixel transistors as a part of comparator for a single-slope ADC instead of using them as an SF. The prototype sensor was fabricated using a 0.35-mum 2P3M CMOS process. Experimental results show 15-times linearity improvement, 26% sensitivity enhancement, and 33% noise reduction over the conventional APS.
Keywords :
CMOS image sensors; analogue-digital conversion; comparators (circuits); transistors; CMOS process; active pixel sensor; column-level single-slope ADC; comparator; low-noise in-pixel; noise reduction; pixel readout noise; pixel transistors; sensitivity degradation; sensitivity enhancement; source follower; Degradation; Dynamic range; Energy consumption; High power amplifiers; Information technology; Linearity; Noise reduction; Power amplifiers; Sampling methods; Signal to noise ratio; CMOS active pixel sensor (APS); column-level ADC; readout noise; source follower (SF);
Journal_Title :
Electron Devices, IEEE Transactions on
DOI :
10.1109/TED.2008.2006735
