PixArt Imaging Inc.
PAS005B
CMOS Image Sensor IC
2. Block Diagram
Averaged
Sub-sampling
function
Color DAC
R:G1:G2:B 8b: magnitude
1b: sign
9b D/A
Image Array
1308x1040
Color Gain
R:G1:G2:B
Global Gain
Front Gain
Frame
ABC-A
CDS
FG
CG
GG
10b A/D
Column decoder
x2~x3.5
(2b)
X1~x2.875
(4b)
X1~x4.1
(5b)
Timing generator
& control logic
Companding
Defect
Compensation
Line
ABC-D
Frame
ABC-D
ABC : Auto-Background Compensation.
Frame ABC-A : Frame based ABC-Analog domain.
Frame ABC-D : Frame based ABC-Digital domain.
Line ABC-D : Line based ABC-Digital domain.
Figure 2.1. Shows the PAS005 sensor block diagram
The PAS005 is a 1/2 –inch CMOS imaging sensor with 1308x1040 physical pixels. The active region of
sensor array is 1288x1028 as shown in Fig. 2.1. The sensor array is cover with Bayer pattern color filters and
U-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 image is sampled first with CDS (Correlated Double Sampling)
block to improve S/N ration and reduce fixed pattern noise. The optional XY-averaged function is
implemented to improve the sub-samapling image quality. It can reduce the sawtooth edge in VGA and CIF
format output.
Three analog gain stages are implemented before signal transferred by the 10b 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/R. The global gain
stage (GG) is programmed to adapt the gain to the image luminance.
The fine gained signal will be digitized by the on-chip 10b ADC. After the image data has been digitized,
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PixArt Imaging Inc.
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PIXART [ PIXART IMAGING INC. ]
