EVAL-ADV7320EB AD [Analog Devices], EVAL-ADV7320EB Datasheet - Page 55

• Manufacturer Part Number: EVAL-ADV7320EB
• Description: Multiformat 216 MHz Video Encoder with Six NSV 12-Bit DACs
• Manufacturer: AD [Analog Devices]

HD SHARPNESS FILTER AND ADAPTIVE FILTER
CONTROLS
[Subaddresses 0x20, 0x38 to 0x3D]
There are three filter modes available on the ADV7320/
ADV7321: sharpness filter mode and two adaptive filter modes.
HD Sharpness Filter Mode
To enhance or attenuate the Y signal in the frequency ranges
shown in Figure 73, the HD sharpness filter must be enabled
and the HD adaptive filter enable must be disabled.
To select one of the 256 individual responses, the corresponding
gain values, which range from –8 to +7, for each filter must be
programmed into the HD sharpness filter gain register at
Address 0x20.
HD Adaptive Filter Mode
The HD adaptive filter threshold A, B, and C registers, the HD
adaptive filter gain 1, 2, and 3 registers, and the HD sharpness
gain register are used in adaptive filter mode. To activate the
adaptive filter control, the HD sharpness filter and the HD
adaptive filter must be enabled.
SIGNAL:
INPUT
STEP

1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
FILTER A RESPONSE (Gain Ka)
FREQUENCY (MHz)
SHARPNESS AND ADAPTIVE FILTER CONTROL BLOCK
Figure 73. Sharpness and Adaptive Filter Control Block
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
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FILTER B RESPONSE (Gain Kb)
FREQUENCY (MHz)
The derivative of the incoming signal is compared to the three
programmable threshold values: HD Adaptive Filter Threshold
A, B, and C. The recommended threshold range is from 16 to
235, although any value in the range of 0 to 255 can be used.
The edges can then be attenuated with the settings in HD
adaptive filter gain 1, 2, and 3 registers, and HD sharpness filter
gain register.
According to the settings of the HD adaptive filter mode
control, there are two adaptive filter modes available:
1.
2.
Mode A is used when adaptive filter mode is set to 0.
In this case, Filter B (LPF) will be used in the adaptive
filter block. Also, only the programmed values for
Gain B in the HD sharpness filter gain and HD
Adaptive Filter Gain 1, 2, and 3 are applied when
needed. The Gain A values are fixed and cannot be
changed.
Mode B is used when adaptive filter mode is set to 1.
In this mode, a cascade of Filter A and Filter B is used.
Both settings for Gain A and Gain B in the HD
sharpness filter gain and HD Adaptive Filter Gain 1, 2,
and 3 become active when needed.
1.6
1.5
1.4
1.3
1.2
1.1
1.0
FREQUENCY RESPONSE IN SHARPNESS
0
FILTER MODE WITH Ka = 3 AND Kb = 7
2
FREQUENCY (MHz)
4
ADV7320/ADV7321
6
8
10
12