Datasheet

13
SLES084C − August 2007 TVP5146
2.2.2.1 Color Low-Pass Filter
High filter bandwidth preserves sharp color transitions and produces crisp color boundaries.
However, for video sources that have asymmetrical U and V side bands, it is desirable to limit
the filter bandwidth to avoid UV crosstalk. The color low-pass filter bandwidth is programmable
to enable one of the three notch filters. Figure 2−4 through Figure 2−7 represent the frequency
responses of the wideband color low-pass filters.
Figure 2−4. Color Low-Pass Filter Frequency
Response
Figure 2−5. Color Low-Pass Filter With Filter
Frequency Response, NTSC Square Pixel
Sampling
f – Frequency – MHz
−70
−60
−50
−40
−30
−20
−10
0
10
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
PAL SQP –3 dB
@ 1.55 MHz
NTSC SQP –3 dB
@ 1.29 MHz
ITU-R BT.601 –3 dB
@ 1.42 MHz
Amplitude − dB
f – Frequency – MHz
−70
−60
−50
−40
−30
−20
−10
0
10
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Amplitude − dB
Filter 0
–3 dB @ 1.29 MHz
Filter 1
–3 dB
@ 936 kHz
Filter 3
–3 dB @ 504 kHz
Filter 2
–3 dB @ 767 kHz
−70
−60
−50
−40
−30
−20
−10
0
10
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Figure 2−6. Color Low-Pass Filter With Filter
Characteristics, NTSC/PAL ITU-R BT.601
Sampling
Figure 2−7. Color Low-Pass Filter With Filter
Characteristics, PAL Square Pixel Sampling
f – Frequency – MHz
−70
−60
−50
−40
−30
−20
−10
0
10
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Amplitude − dB
Filter 3
–3 dB @ 554 kHz
Filter 2
–3 dB @ 844 kHz
Filter 1
–3 dB
@ 1.03 MHz
Filter 0
–3 dB @ 1.41 MHz
f – Frequency – MHz
Amplitude − dB
Filter 3
–3 dB
@ 605 kHz
Filter 0
–3 dB @ 1.55 MHz
Filter 2
–3 dB @ 922 kHz
Filter 1
–3 dB
@ 1.13 MHz