DDP3310B Datasheet, PDF (7/60 Pages) Micronas – Display and Deflection Processor

ADVANCE INFORMATION
DDP 3310B
2.1.4. Dynamic Peaking
Especially with decoded composite signals and notch
filter luminance separation as input signals, it is neces-
sary to improve the luminance frequency characteris-
tics. With transparent high-bandwidth signals, it is
sometimes desirable to soften the image.
In the DDP 3310B, the luma frequency response is
improved by “dynamic” peaking. It adapts to the ampli-
tude and the frequency of the input signal. Small AC
amplitudes are sharpened while large AC amplitudes
remain nearly unmodified.
The dynamic range can be adjusted from −14 to
+14 dB for small high-frequency signals. There is sep-
arate adjustment for signal overshoot and for signal
undershoot. For large signals, the dynamic range is
limited by a non-linear function that does not create
any visible alias components. The peaking can be
switched over to “softening” by inverting the peaking
term by software.
The center frequency of the peaking filter is selectable
from 2.5 MHz to 3.2 MHz. For S-VHS and for notch fil-
ter color decoding, the total system frequency
responses for both PAL and NTSC are shown in Fig.
2–1 and Fig. 2–2. (All frequencies refer to a 50/60-Hz
video signal).
dB
20
15
10
5
0
-5
-10
-15
-20
0
2
4
6
8
MHz
10
Fig. 2–1: Dynamic peaking frequency response
dB
20
15
10
CF= 3.2 MHz
dB
20
15
10
5
5
0
S-VHS ⁰
-5
-5
-10
-10
-15
-20
MHz
0
2
4
6
8
10
-15
-20
0
2
4
dB
20
15
CF= 3.2 MHz
dB
20
15
10
10
5
5
0
PAL/SECAM ⁰
-5
-5
-10
-10
-15
-20
MHz
0
2
4
6
8
10
-15
-20
0
2
4
dB
20
15
CF= 3.2 MHz
dB
20
15
10
10
5
5
0
NTSC
0
-5
-5
-10
-10
-15
-20
MHz
0
2
4
6
8
10
-15
-20
0
2
4
Fig. 2–2: Total frequency response for peaking filter and S-VHS, PAL, NTSC
CF= 2.5 MHz
MHz
6
8
10
CF= 2.5 MHz
6
8
MHz
10
CF= 2.5 MHz
6
8
MHz
10
Micronas
7