adv7195 Analog Devices, Inc., adv7195 Datasheet - Page 22

• Manufacturer Part Number: adv7195
• Description: Encoder With Three 11-bit Dacs And 10-bit Data Input
• Manufacturer: Analog Devices, Inc.

ADV7195
The gamma curves shown in Figure 36 are examples only, any
user-defined curve is acceptable in the range of 16–240.
SHARPNESS FILTER CONTROL AND ADAPTIVE
FILTER CONTROL
Three Filter modes are available on the ADV7195: one Sharpness
Filter mode and two Adaptive Filter modes.
SHARPNESS FILTER MODE
To enhance or attenuate the Y signal in the frequency ranges
shown in Figure 37, the following register settings must be used:
Sharpness Filter must be enabled (MR17 = “1”) and Adaptive
Filter Control must be disabled (MR57 = “0”).
To select one of the 256 individual responses, the according
gain values for each filter, which range from –8 to +7, must be
programmed into the Filter Gain register.
ADAPTIVE FILTER MODE
The Adaptive Filter Threshold A, B, C registers, the Adaptive
Filter Gain 1, 2, 3 registers, and the Filter Gain register are used
in Adaptive Filter mode. To activate the Adaptive Filter control,
Sharpness Filter must be enabled (MR17 = “1”) and Adaptive
Filter Control must be enabled (MR57 = “1”).
The derivative of the incoming signal is compared to the three
programmable threshold values: Adaptive Filter Threshold
A, B, C.
The edges can then be attenuated with the settings in Adaptive
Filter Gain 1, 2, 3 registers and Filter Gain register.
According to the settings of the Adaptive Mode control (MR56),
two Adaptive Filter Modes are available:
1. Mode A: is used when Adaptive Filter Mode (MR56) is set
2. Mode B: is used when Adaptive Filter Mode (MR56) is set
to “0.” In this case, Filter B (LPF) will be used in the adap-
tive filter block. Also, only the programmed values for
Gain B in the Filter Gain, Adaptive Filter Gain 1, 2, 3 are
applied when needed. The Gain A values are fixed and can-
not be changed.
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 Filter Gain,
Adaptive Filter Gain 1, 2, 3 become active when needed.
300
250
200
150
100
50
0
0
GAMMA CORRECTION BLOCK OUTPUT
TO A RAMP INPUT FOR VARIOUS GAMMA VALUES
50
0.3
100
1.5
0.5
SIGNAL OUTPUTS
LOCATION
1.8
150
200
250
FREQUENCY RESPONSE IN SHARPNESS FILTER MODE
WITH K
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
1.6
1.5
1.4
1.3
1.2
1.1
1.0
SHARPNESS AND ADAPTIVE FILTER CONTROL MODE
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0
0
0
A
= 3 and K
2
2
2
B
INPUT SIGNAL: STEP
= 7
4
4
4
FREQUENCY – MHz
FREQUENCY – MHz
FREQUENCY – MHz
6
6
6
–1
–2
–3
–4
–5
–6
–7
–8
6
5
4
3
2
1
0
7
8
8
8
10
10
10
12
12
12
–1
–2
–3
–4
–5
–6
–7
–8
7
6
5
4
3
2
1
0
14
14
14