ADV7341_15 datasheet(64/108 Pages) AD

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ADV7340/ADV7341

Data Sheet

Rev. C | Page 64 of 108

ED/HD SHARPNESS FILTER AND ADAPTIVE

FILTER CONTROLS

Subaddress 0x40; Subaddress 0x58 to Subaddress 0x5D

There are three filter modes available on the ADV7340/ADV7341:

a sharpness filter mode and two adaptive filter modes.

ED/HD Sharpness Filter Mode

To enhance or attenuate the Y signal in the frequency ranges

shown in Figure 69, the ED/HD sharpness filter must be

enabled (Subaddress 0x31, Bit 7) and the ED/HD adaptive filter

must be disabled (Subaddress 0x35, Bit 7).

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 ED/HD sharpness filter gain register at

Subaddress 0x40.

ED/HD Adaptive Filter Mode

The ED/HD adaptive filter (Threshold A, Threshold B, and

Threshold C) registers, the ED/HD adaptive filter (Gain 1,Gain 2,

and Gain 3) registers, and the ED/HD sharpness filter gain

adaptive filter control, the ED/HD sharpness filter and the

ED/HD adaptive filter must be enabled (Subaddress 0x31, Bit 7,

and Subaddress 0x35, Bit 7, respectively).

The derivative of the incoming signal is compared to the

three programmable threshold values; that is the ED/HD

adaptive filter (Threshold A, Threshold B, and Threshold C)

registers (Subaddress 0x5B, Subaddress 0x5C, and Subaddress

0x5D, respectively). The recommended threshold range is 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 the

ED/HD adaptive filter (Gain 1, Gain 2, and Gain 3) registers

(Subaddress 0x58, Subaddress 0x59, and Subaddress 0x5A,

respectively), and the ED/HD sharpness filter gain register

(Subaddress 0x40).

There are two adaptive filter modes available. The mode

is selected using the ED/HD adaptive filter mode control

(Subaddress 0x35, Bit 6) as follows:

•

Mode A is used when the ED/HD adaptive filter mode

control is set to 0. In this case, Filter B (LPF) is used in the

adaptive filter block. In addition, only the programmed

values for Gain B in the ED/HD sharpness filter gain

Gain 3) registers are applied when needed. The Gain A

values are fixed and cannot be changed.

•

Mode B is used when ED/HD adaptive filter mode control

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 ED/HD

sharpness filter gain register and ED/HD adaptive filter

(Gain 1, Gain 2, and Gain 3) registers become active when

needed.

Figure 69. ED/HD Sharpness and Adaptive Filter Control Block

FREQUENCY (MHz)

FILTER A RESPONSE (Gain Ka)

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

FREQUENCY (MHz)

FILTER B RESPONSE (Gain Kb)

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

FREQUENCY (MHz)

1.0

1.1

1.2

1.3

1.4

1.5

1.6

INPUT

SIGNAL

STEP

FREQUENCY RESPONSE IN SHARPNESS

FILTER MODE WITH Ka = 3 AND Kb = 7

SHARPNESS AND ADAPTIVE FILTER CONTROL BLOCK

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