LUPA-1300 Datasheet, PDF (16/48 Pages) Cypress Semiconductor – 1.3 M Pixel High Speed CMOS Image Sensor

LUPA-1300
Datasheet
3.3 Output amplifiers
16 output amplifiers each capable of working at 40MHz pixel rate are placed
equidistant on the bottom of the image sensor. These output amplifiers are required to
obtain a frame rate of 450 frames/sec. A single output stage, not only to reduce
power, but also to achieve the required pixel rate is designed. Figure 6 is a schematic
representation of this module.
Stabilize power
supply
Vstable
In
Out
Output stage load
Cload ≤ 10 pF
Figure 6: schematic representation of a single output stage.
Each output stage is designed to drive a load of 10pF at a pixel rate of 40MHz. The
load in the output stage determines this pixel rate. In case the load capacitance is less
than 10pF, the load in the output stage can increase, resulting in less power
dissipation of the output stages and consequently of the whole sensor. Additionally,
decreasing the load of the output stage allows having more current available for the
output stage to charge or discharge the load capacitance to obtain a higher pixel rate.
To avoid variations on the supply voltage to be seen on the output signal, a special
module to stabilize the power supply is required. This module that requires an
additional supply voltage (Vstable) allows variation on the supply voltage Voo
without being seen on the output signal.
One can also choose to have a passive load of chip instead of the active output stage
load. This deteriorates the linearity of the output stages, but decreases the power
dissipation, as the dissipation in the load is external.
Note: The LUPA-1300 is designed to drive a capacitive load, not a resistive. When
one wants to transport the output signals over long distances (more than 1 inch), make
sure to place buffers on the outputs with high input impedances (preferably
>1Mohms). This is necessary because the output impedance of the LUPA-1300 is
between 200-300 ohms typically.
Cypress Semiconductor Corporation 3901 North First Street
San Jose, CA 95134 408-943-2600
Contact [e-mail] Document # : 38-05711 Rev.**( Revision 3.1) Page 16 of 48