PYTHON25K Datasheet, PDF (86/87 Pages) ON Semiconductor – PYTHON 25K/16K/12K/10K Global Shutter CMOS Image Sensors

NOIP1SN025KA, NOIP1SN016KA, NOIP1SN012KA, NOIP1SN010KA
GLOSSARY
conversion gain
CDS
CFA
DNL
DSNU
fill-factor
INL
IR
Lux
pixel noise
photometric units
PLS
PRNU
QE
read noise
reset
reset noise
responsivity
ROI
sense node
sensitivity
spectral response
SNR
temporal noise
A constant that converts the number of electrons collected by a pixel into the voltage swing of the pixel.
Conversion gain = q/C where q is the charge of an electron (1.602E 19 Coulomb) and C is the capacitance
of the photodiode or sense node.
Correlated double sampling. This is a method for sampling a pixel where the pixel voltage after reset is
sampled and subtracted from the voltage after exposure to light.
Color filter array. The materials deposited on top of pixels that selectively transmit color.
Differential non-linearity (for ADCs)
Dark signal non-uniformity. This parameter characterizes the degree of non-uniformity in dark leakage
currents, which can be a major source of fixed pattern noise.
A parameter that characterizes the optically active percentage of a pixel. In theory, it is the ratio of the
actual QE of a pixel divided by the QE of a photodiode of equal area. In practice, it is never measured.
Integral nonlinearity (for ADCs)
Infrared. IR light has wavelengths in the approximate range 750 nm to 1 mm.
Photometric unit of luminance (at 550 nm, 1lux = 1 lumen/m² = 1/683 W/m²)
Variation of pixel signals within a region of interest (ROI). The ROI typically is a rectangular portion of the
pixel array and may be limited to a single color plane.
Units for light measurement that take into account human physiology.
Parasitic light sensitivity. Parasitic discharge of sampled information in pixels that have storage nodes.
Photo-response non-uniformity. This parameter characterizes the spread in response of pixels, which is a
source of FPN under illumination.
Quantum efficiency. This parameter characterizes the effectiveness of a pixel in capturing photons and
converting them into electrons. It is photon wavelength and pixel color dependent.
Noise associated with all circuitry that measures and converts the voltage on a sense node or photodiode
into an output signal.
The process by which a pixel photodiode or sense node is cleared of electrons. ”Soft” reset occurs when
the reset transistor is operated below the threshold. ”Hard” reset occurs when the reset transistor is oper-
ated above threshold.
Noise due to variation in the reset level of a pixel. In 3T pixel designs, this noise has a component (in units
of volts) proportionality constant depending on how the pixel is reset (such as hard and soft). In 4T pixel
designs, reset noise can be removed with CDS.
The standard measure of photodiode performance (regardless of whether it is in an imager or not). Units
are typically A/W and are dependent on the incident light wavelength. Note that responsivity and sensitivity
are used interchangeably in image sensor characterization literature so it is best to check the units.
Region of interest. The area within a pixel array chosen to characterize noise, signal, crosstalk, and so on.
The ROI can be the entire array or a small subsection; it can be confined to a single color plane.
In 4T pixel designs, a capacitor used to convert charge into voltage. In 3T pixel designs it is the photodi-
ode itself.
A measure of pixel performance that characterizes the rise of the photodiode or sense node signal in Volts
upon illumination with light. Units are typically V/(W/m²)/sec and are dependent on the incident light wave-
length. Sensitivity measurements are often taken with 550 nm incident light. At this wavelength, 1 683 lux
is equal to 1 W/m²; the units of sensitivity are quoted in V/lux/sec. Note that responsivity and sensitivity are
used interchangeably in image sensor characterization literature so it is best to check the units.
The photon wavelength dependence of sensitivity or responsivity.
Signal-to-noise ratio. This number characterizes the ratio of the fundamental signal to the noise spectrum
up to half the Nyquist frequency.
Noise that varies from frame to frame. In a video stream, temporal noise is visible as twinkling pixels.
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