PixArt Imaging Inc.

PAC207BCA

Single-Chip CIF CMOS Image sensor with USB

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5

V1.3, June. 2004

5. FUNCTIONAL DESCRIPTION

5.1 ANALOG DATA PATH

9-bit

+/-250mV

DAC

dac[8:0]

Global gain

5-bits

10-bit

pipelined

ADC

X4

Color gain

B,G1,G2,R

4-bits

X3

X1/4, 1/2, 1, 2

Sensor Array

CDS

Col. Decoders

X3.5

Front gain

2-bits

step code[1:0]

PAC207B embedded a high quality CMOS image sensor with Pixart advanced sensor

structure. With correlated-double-sampling (CDS) circuit, it cancelled the column-wise fixed

pattern noise (FPN) and pixel mismatch at sensing node for each pixel. Hence PAC207B can

deliever a clean image quality.

With a progressive scanning timing, the analog pixel signal is transferred into “Front-Gain”

stage. Then transferred the pre-amplifier analog signal into programmable gain amplifier

(PGA). Then ADC will convert the analog signal into a 10 bit digital code.

The gain stage can be set by digital register setting, please refer to the following equation to

get the mapping gain.

Front Gain =

2+(n/2),

n = 0, 1, 2, 3

Color Gain =

1+(m/8),

m= 0, 1, 2, …15

Global Gain =

1+(q/10),

q = 0, 1, 2, …31