LUPA-1300 Datasheet, PDF (15/48 Pages) Cypress Semiconductor – 1.3 M Pixel High Speed CMOS Image Sensor

LUPA-1300
Datasheet
3.2 Column readout amplifiers
The column readout amplifiers are the interface between the pixels and the output
amplifiers. The pixels in the array are selected line by line and the pixels of the
selected line are connected to the column readout amplifiers, which bring the pixel
data in the correct format to the output amplifiers.
To obtain a high frame rate, the complexity and the number of stages in the column
readout amplifiers must be minimized, so that the power dissipation remains as low as
possible, but also to minimize the row blanking time. Figure 5 is a schematic
representation of the column readout structure. It consists of 2 parts. The first part is
a module that reduces the row blanking time. The second part shifts the signal to the
correct level for the output amplifiers and allows multiplexing in the x-direction.
From the moment that a new row is selected, the pixel data of that row is placed onto
the columns of the pixel array. These columns are long lines and have a large
parasitic capacitance. As the pixel is small, it is not possible to match the transistor
inside the pixel, which drives this column. Consequently, the first module in the
column readout amplifiers must solve the mismatch between the pixel driver and the
large column capacitance.
column
Module 1 : track & hold or reference set method
Sh kol
Norow sel
Module 2 : signal conditioning and multiplexing
X-mux
Output stage
Figure 5: Schematic representation of the column readout structure.
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Contact [e-mail] Document # : 38-05711 Rev.**( Revision 3.1) Page 15 of 48