PixArt Imaging Inc.

PAS005B

CMOS Image Sensor IC

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PixArt Imaging Inc.

2. Block Diagram

Image Array

1308x1040

CDS

Column decoder

FG

GG

CG

10b A/D

9b D/A

Frame

ABC-A

Frame

ABC-D

Line

ABC-D

x2~x3.5

(2b)

X1~x2.875

(4b)

X1~x4.1

(5b)

1b: sign

8b: magnitude

Defect

Compensation

Timing generator

& control logic

Front Gain

Color Gain

R:G1:G2:B

Global Gain

Color DAC

R:G1:G2:B

Companding

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.

Averaged

Sub-sampling

function

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,