A 640 512 CMOS Image Sensor with Ultrawide Dynamic Range Floating-Point Pixel-Level ADC (1999)
| Venue: | IEEE Journal of Solid-State Circuits |
| Citations: | 18 - 5 self |
BibTeX
@ARTICLE{Yang99a640,
author = {David X. D. Yang and Abbas El Gamal and Boyd Fowler and Hui Tian},
title = {A 640 512 CMOS Image Sensor with Ultrawide Dynamic Range Floating-Point Pixel-Level ADC},
journal = {IEEE Journal of Solid-State Circuits},
year = {1999},
volume = {34},
pages = {1821--1834}
}
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Abstract
A 640×512 CMOS image sensor with an 8b bit-serial Nyquist rate ADC per 4 pixels achieves 10.5 × 10.5 µm pixel size at 29 % fill factor in 0.35 µm CMOS technology. Binary floating point output with measured dynamic range of of 65536: 1 is achieved by multiple sampling at exponentially increasing exposure times. D.Yang,A.ElGamal,B.Fowler,andH.Tian 1 Dynamic range, defined as the ratio of the largest nonsaturating signal to the standard deviation of the noise under dark conditions, is a critical figure of merit for image sensors. The dynamic range of an image sensor is often not wide enough to capture scenes with both high lights and dark shadows. This is especially the case for CMOS sensors, which, in general, have lower dynamic range than CCDs. Several approaches have been proposed to enhance the dynamic range of a CMOS APS. In [1] dynamic range is enhanced by increasing well capacity one or more times during exposure time. Another approach, which achieves consistently higher SNR, is multiple sampling. Here the scene is imaged several times at different exposure times and the data is combined to construct a high dynamic range image.
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