KAI−04022
www.onsemi.com
19
Global Peak to Peak Non-Uniformity
This test is performed with the imager illuminated to
a level such that the output is at 70% of saturation
(approximately 86 8 mV). Prior to this test being performed
the substrate voltage has been set such that the charge
capacity o f the sensor is 1,240 mV. The sensor is partitioned
into 256 sub regions of interest, each of which is 128 by 128
pixels i n size. The average signal level of each of the 256 sub
regions of interest (ROI) is calculated. The signal level of
each of the sub regions of interest is calculated using the
following formula:
A[i] +(ROI Average *Horizontal Overclock Average)
Where i = 1 t o 256. During this calculation on the 256 sub
regions of interest, the maximum and minimum average
signal levels are found. The global peak to peak
non−uniformity is then calculated as:
Global Non−Uniformity +100 @A[i] Max. Signal *A[i] Min. Signal
Active Area Signal
Units : % pp
Active Area Signal = Active Area Average − H. Column Average
Center Non-Uniformity
This test is performed with the imager illuminated to
a level such that the output is at 70% of saturation
(approximately 86 8 mV). Prior to this test being performed
the substrate voltage has been set such that the charge
capacity of the sensor is 1,240 mV. Defects are excluded for
the calculation of this test. This test is performed on the
center 100 by 100 pixels (See Test Regions of Interest ) of
the sensor. Center non-uniformity is defined as:
Center ROI Non−Uniformity +100 @Center ROI Standard Deviation
Center ROI Signal
Center ROI Signal = Center ROI Average −H. Colum Average
Units : % rms
Dark Field Defect Test
This test is performed under dark field conditions.
The sensor is partitioned into 256 sub regions of interest,
each of which is 128 by 128 pixels in size. In each region of
interest, the median value of all pixels is found. For each
region of interest, a pixel is marked defective if it is greater
than or equal to the median value of that region of interest
plus the defect threshold specified in “Defect Definitions”
section.
Bright Field Defect Test
This test is performed with the imager illuminated to
a level such that the output is at 70% of saturation
(approximately 28,000 electrons). Prior to this test being
performed the substrate voltage has been set such that the
charge capacity of the sensor is 40,000 electrons.
The average signal level of all active pixels is found.
The bright and dark thresholds are set as:
Dark Defect Threshold = Active Area Signal @Threshold
Bright Defect Threshold = Active Area Signal @Threshold
The sensor is then partitioned into 256 sub regions of
interest, each of which is 128 by 128 pixels in size. In each
region of interest, the average value of all pixels is found.
For each region of interest, a pixel is marked defective if it
is greater than or equal to the median value of that region of
interest plus the bright threshold specified or if it is less than
or equal to the median value of that region of interest minus
the dark threshold specified.
Example for major bright field defective pixels:
•Average value of all active pixels is found to be
868 mV (28,000 electrons)
•Dark defect threshold: 868 mV ⋅ 15% = 130.2 mV
•Bright defect threshold: 868 mV ⋅ 15% = 130.2 mV
•Region of interest #1 selected. This region of interest is
pixels 1,1 to pixels 128,128
♦Median of this region of interest is found to be
868 mV.
♦Any pixel in this region of interest that is
≥(868 + 130.2 mV) 998.2 mV in intensity will be
marked defective.
♦Any pixel in this region of interest that is
≤(868 − 130.2 mV) 737.8 mV in intensity will be
marked defective.
•All remaining 255 sub-regions of interest are analyzed
for defective pixels in the same manner