PAS302BCA-32 Datasheet, PDF (4/15 Pages) Pixart Imaging Inc. – CMOS VGA DIGITAL IMAGE SENSOR

PAS302BCA-32
2. Block Diagram
CMOS Image Sensor IC
Sensor Array
644x484
CDS
Column Decoder
Front Gain
FG
3-Bit
x2 ~ x4
Color Gain
CG
DAC1
4-Bit
x1 ~ x2
Global Gain
GG
4-Bit
x1 ~ x2
DAC2
10-Bit
A/D
Timing Generator & Control Logic
Companding
Digital Gain
Stage
Defect
Compensation
Figure 2.1. PAS302BCA-32 sensor block diagram
The PAS302BCA-32 is a 1/4” CMOS imaging sensor with 644x488 physical pixels. The active
region of sensor array is 644x484 as shown in Fig. 2.1. The sensor array is covered with Bayer
pattern color filters and micro-lens. The first pixel location <0,0> is programmable in 2 direction
(X and Y) and the default value is at the left-down side of sensor array.
After a programmable exposure time, the signals of image are sampled first with CDS
(Correlated Double Sampling) block to improve S/N ratio and reduce fixed pattern noise.
Three analog gain stages are implemented before signals are transferred to 10-Bit ADC. The
front gain stage (FG) can be programmed to fit the saturation level of sensor to the full-range
input of ADC. The programmable color gain stage (CG) is used to balance the luminance
response difference between B, G and R color. The global gain stage (GG) is programmed to
adapt the gain to the image luminance.
After three gain stages, the signals will be digitized by the on-chip 10-Bit ADC. After the image
data have been digitized, further adjustment to the signal can be applied before the data is
output to next stage.
Version 2.3, 13 Sep. 2004
PixArt Imaging Inc.
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