IBIS4-6600 Datasheet, PDF (27/63 Pages) Cypress Semiconductor – High resolution 6.6 M Pixel Rolling shutter CMOS Image sensor

IBIS4-6600
Datasheet
sensitivity, thus the output signal level at which the transition between high
and low sensitivity occurs.
Put the amplifier gain to the lowest value where the analog output swing
covers the ADC’s digital input swing. Increasing the amplification too much
will likely boost the high sensitivity part over the whole ADC range.
The electronic shutter determines the ratio of integration times of the two
slopes. The high sensitivity ramp corresponds to “no electronic shutter”, thus
maximal integration time (frame read out time). The low sensitivity ramp
corresponds to the electronic shutter value that would have been obtained in
normal operation.
Examples of the double slope (high dynamic range) mode can be found at
http://www.fillfactory.be/htm/technology/htm/dual-slope.htm.
3.8.2 Non-destructive readout (NDR)
The default mode of operation of the sensor is with FPN correction (double
sampling). However, 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.
time
Figure 17. Principle of non-destructive readout.
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 11
summarizes the advantages and disadvantages of non-destructive readout.
Table 11: Advantages and disadvantages of non-destructive readout.
Advantages
Low noise – as it is true CDS. In the
order of 10 e- or below.
High sensitivity – as the conversion
capacitance is kept rather low.
Disadvantages
System memory required to record the
reset level and the intermediate samples.
Requires multiples readings of each pixel,
thus higher data throughput.
Cypress Semiconductor Corporation 3901 North First Street
San Jose, CA 95134
408-943-2600
Contact: [e-mail] Document #: 38-05708 Rev.**(Revision 1.3 )
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