ADV7177 Datasheet, PDF (36/38 Pages) Analog Devices – Integrated Digital CCIR-601 to PAL/NTSC Video Encoder

ADV7177/ADV7178
APPENDIX 5
OPTIONAL OUTPUT FILTER
If an output filter is required for the CVBS, Y, UV, Chroma and
RGB outputs of the ADV7177/ADV7178, the following filter in
Figure 63 can be used. Plots of the filter characteristics are
shown in Figures 64, 65 and 66. An output filter is not required
if the outputs of the ADV7177/ADV7178 are connected to an
analog monitor or an analog TV; however, if the output signals
are applied to a system where sampling is used (e.g., digital
TV), a filter is required to prevent aliasing.
L
1␮H
IN
R
75⍀
L
2.7␮H
C
470pF
L
0.68␮H
C
330pF
C
56pF
OUT
R
75⍀
Figure 63. Output Filter
0
V_dB – OP
–5
–10
–15
–20
–25
–30
–35
1
10
100
FREQUENCY – MHz
Figure 65. Output Filter Close Up
0
–5
–10 ^VdB ^{– OP}
–15
–20
–25
–30
–35
–40
–45
–50
–55
–60
–65
–70
10k
100k
1M
10M
FREQUENCY – Hz
Figure 64. Output Filter Plot
100M
0.0
–0.5
V_dB – OP
–1.0
–1.5
–2.0
–2.5
–3.0
–3.5
–4.0
–4.5
1
2
4
6
FREQUENCY – MHz
8 10
Figure 66. Output Filter Plot Close Up
–36–
REV. 0