A CMOS Log Image Sensor with on-chip FPN Compensation Yang NI
Karine MATOU
Departement Electronique et Physique, Institut National des Telecommunications 9, rue Charles Fourier Evry, France. Email
[email protected]
Abstract
temperature, power supply voltage, etc. . Because in
This paper describes a logarithmic image
such Log sensor, an electronic dark image reference is
sensor in CMOS technology by using photodiode in
not possible and the dark FPN reference image can
photovoltaic mode. Thanks to this pixel design, an
only be obtained optically, it is difficult to update the
electronic dark image reference can be obtained for
image reference during the usage of such camera
each pixel readout and a fixed pattern noise (FPN)
system. So the practical usefulness of a Log sensor in
compensation can be easily done by on-chip analog
vision systems implies the following improvements to
circuits. A 160x120-pixel prototype circuit in a
actual Log imagers : 1° simpler and more stable FPN
standard 0.8um DPDM CMOS technology will be
compensation method; 2° better sensitivity in low light
described. This prototype chip has demonstrated low
conditions; 3° reduction of image lag in dim
FPN, high dynamic range and high sensitivity at low
conditions. Here we have invented a new log image
light condition (
