Lexmark OptraImage 443 Service Manual page 18

2. CCD signal processing circuit
R
CCD MUX
G
B
The video noise suppression circuit is to eliminate the reset noise and low frequency noise of CCD and
then PGA performs video gain control.
satisfy the reference bottom requirement of the A/D converter. The "DC-OFFSET Adjust" circuit is used
to adjust the bias level of video signal.
* PGA: Programmable gain amplifier
Lexmark Internal Use Only
Video Noise
Suppression PGA*
Circuit
DC Offset
Adjust Circuit
The "level shift" circuit is used to bias the PGA output to
1-14
Level A/D
Converter
Shift