STAR1000_11 Datasheet, PDF (22/24 Pages) Cypress Semiconductor – 1M Pixel Radiation Hard CMOS Image Sensor

Glossary
conversion gain
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
STAR1000
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.
Differential nonlinearity (for ADCs)
Dark signal nonuniformity. This parameter characterizes the degree of nonuniformity 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 nonuniformity. 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 operated 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
photodiode 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 wavelength. 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.
Document Number: 38-05714 Rev. *F
Page 22 of 24
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