LUPA-4000 Datasheet, PDF (14/49 Pages) Cypress Semiconductor – 4M Pixel CMOS Image Sensor

LUPA-4000
Data Sheet
3.3 Output amplifier
1 output amplifier working at 66Mpixels/sec is required to bring the whole pixel array
of 2048 by 2048 pixels at the required frame rate to the outside world. A second
output stage is also foreseen to convert the analog data on-chip by 2 10-bit ADC’s
each working at 33 MHz. By having a second output stage working in parallel, the
pixel rate can be more relaxed to 33MHz for both output amplifiers. Using only one
output-stage, the output signal will be the result of multiplexing between the 2 internal
buses. When using 2 output-stages, both outputs will be in phase.
Each output-stage has 2 outputs. One output is the pixel signal; the second output is a
DC signal which offset can be programmed using a 7-bit word. The DC signal can be
used for common mode rejection between the 2 signals. The disadvantage is an
increase in power dissipation however this can be reduced by setting the highest DAC
voltage by means of the SPI.
Image sensor
Out1: Pixel signal
7bits
SPI
DAC
Out2: dc signal
Figure 5: Output stage architecture
The output voltage of Out1 will be between 1.3V (dark level) and 0.3V (white level)
and depends on process variations and voltage supply settings. The output voltage of
Out2 is determined by the DAC.
3.4 Pixel array drivers
We have foreseen on this image sensor on chip drivers for the pixel array signals. Not
only the driving on system level is easy and flexible, also the maximum currents
applied to the sensor are controlled on chip. This means that the charging on sensor
level is fixed and that the sensor cannot be overdriven from externally. In the
paragraph on the timing, the operation of the on-chip drivers is explained more in
detail.
Cypress Semiconductor Corporation
3901 North First Street
San Jose, CA 95134
408-943-2600
Contact: [e-mail] Document #: 38-05712 Rev.**(Revision 1.2 )
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