saa7118 NXP Semiconductors, saa7118 Datasheet - Page 18

• Manufacturer Part Number: saa7118
• Description: Multistandard Video Decoder With Adaptive Comb Filter And Component Video Input
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 15219
Product data sheet
8.1.1.2 Gain control
The gain control circuit receives (via the I
amplifiers or controls one of these amplifiers automatically via a built-in Automatic Gain
Control (AGC) as part of the Analog Input Control (AICO).
The AGC for luminance is used to amplify a CVBS or Y signal to the required signal
amplitude, matched to the ADCs input voltage range. Component inputs are gain adjusted
manually at a fixed gain. The AGC active time is the sync bottom of the video signal.
Signal (white) peak control limits the gain at signal overshoots. The flow charts
(see
voltage variation within the specified range is automatically eliminated by clamp and
automatic gain control.
Fig 7. Analog line with clamp (HCL) and gain range (HSY)
Fig 8. Automatic gain range
Figure 9
and
Figure
Rev. 06 — 22 December 2005
(1 V (p-p) 18/56 )
10) show more details of the AGC. The influence of supply
511
120
1
Multistandard video decoder with adaptive comb filter
analog input level
0 dB
3 dB
6 dB
analog line blanking
maximum
minimum
GAIN
HSY
2
range 9 dB
C-bus) the static gain levels for the four analog
CLAMP
TV line
HCL
ADC input level
mhb325
controlled
mhb726
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
0 dB
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