CYIH1SM1000AA-HHCS Datasheet, PDF (48/71 Pages) Cypress Semiconductor – Detailed Specification - ICD

CYIH1SM1000AA-HHCS
8.2 Image Sensor Operation
The following s describe the HAS' two readout mechanisms and
give the detailed timing and control diagrams to implement these
mechanisms.
8.2.1 Double Sampling - Destructive Readout
In Double Sampling / Destructive Readout (DS/DR) mode the
YRST pointer runs over the frame, top to bottom, each time
resetting the line it addresses. Lagging behind this runs the YRD
pointer, each time reading out the line it addresses. The distance
between the YRD pointer and the YRD pointer is then propor-
tional to the exposure time, hence the electronic shutter
operation.
At line readout the signal levels of the pixels in the addressed
line are copied onto the column amplifiers' signal sample nodes.
Immediately after this the line of pixels is reset, and the pixels'
black levels are copied onto the column amplifiers' reset sample
nodes. This is destructive readout.
The column amplifiers/PGA then subtract the black levels from
the signal levels during sequential pixel out. This is uncorrelated
double sampling, eliminating any static pixel-to-pixel offsets of
the sensor array.
Figure 31. Double Sampling: Pixel signal is read (s), then pixel is reset, then reset level is read (r)
8.2.2 Correlated Double Sampling - Non-Destructive Readout
In Correlated Double Sampling/Non-Destructive Readout (CDS/NDR) mode the YRST or YRD pointer quickly runs over the frame,
top to bottom, resetting each line it addresses. This leaves the pixel array drained of charges, in black or dark state.
Then the YRD or YRST pointer is run over the region of interest of the frame, and of each line addressed the pixels' black levels are
read out and passed on to the ADC. The user stores these black levels in an off-chip frame-sized memory.
Then the system is held idling during the exposure time.
After the exposure time has elapsed, the frame is scanned once more with the YRD or YRST pointer, and each line addressed is read
out again. These signal levels are passed on to the ADC and then to the end user. At the same time, the user retrieves the corre-
sponding black levels from the memory and subtracts them from the signal levels. This is correlated double sampling, eliminating
static offsets as well as kTC noise
Document Number: 001-54123 Rev. *A
Page 48 of 71
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