LUPA-1300_09 Datasheet, PDF (12/32 Pages) Cypress Semiconductor – 1.3MPxl High Speed CMOS Image Sensor

LUPA-1300
Figure 9. Integration and read out in parallel
Read frame I
Read frame I + 1
Integration I + 1
Integration I + 2
The control of the readout of the frame and of the integration
time are independent of each other with the only exception that
the end of the integration time from frame I+1 is the beginning
of the readout of frame I+1.
Non-destructive readout (NDR)
The sensor can also be read out in a non-destructive way. After
a pixel is initially reset, it can be read multiple times, without
resetting. The initial reset level and all intermediate signals can
be recorded. High light levels will saturate the pixels quickly,
but a useful signal is obtained from the early samples. For low
light levels, one has to use the later or latest samples.
Figure 10. Principle of non-destructive readout.
time
Essentially an active pixel array is read multiple times, and
reset only once. The external system intelligence takes care
of the interpretation of the data. Table 6 summarizes the
advantages and disadvantages of non-destructive readout.
Table 6. Advantages and disadvantages of non-destruc-
tive readout.
Advantages
Disadvantages
Low noise - as it is true CDS. System memory required to
record the reset level and the
intermediate samples.
High sensitivity - as the
conversion capacitance is
kept rather low.
Requires multiples readings
of each pixel, thus higher data
throughput.
High dynamic range - as the
results includes signal for
short and long integrations
times.
Requires system level digital
calculations.
Operation and signaling
One can distinguish the different signals into different groups:
• Power supplies and grounds
• Biasing and analog signals
• Pixel array signals
• Digital signals
• Test signals
Power supplies and grounds
Every module on chip, as there are: column readout, output
stages, digital modules, drivers, has its own power supply and
ground. Off chip the grounds can be combined, but not all
power supplies may be combined. This results in several
power supplies, but is required to reduce electrical crosstalk
and to improve shielding.
On chip we have the ground lines also separately for every
module to improve shielding and electrical crosstalk between
them. The only special ground is "Gnd_res", which can be
used to remove the blooming if any and which can improve
optical crosstalk.
An overview of the supplies is given in Table 7. The power
supplies related to the pixel array signals are described in the
paragraph concerning the pixel array signals.
Note
9. Normal application doesn't require this Gnd_res and it can be connected to ground.
Document Number: 38-05711 Rev. *C
Page 12 of 32
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