Data Sheet

AD8143

Rev. A | Page 23 of 24

The AD8134 encoding equations are given in Equation 3,

Equation 4, and Equation 5.

(

)

H

V

K

V

Red

CM

−

=

2

(3)

(

)

V

2

2

−

=

K

V

Green

CM

(4)

(

)

H

V

K

V

Blue

CM

+

=

2

(5)

where:

mode voltages of the respective color signals.

K is an adjustable gain constant that is set by the AD8134.

V and H are the vertical and horizontal sync pulses, defined

with a weight of −1 when the pulses are in their low states, and a

weight of +1 when they are in their high states.

The AD8134 data sheet contains further details regarding the

encoding scheme.

Figure 48 illustrates how the AD8143 comparators can be used

to extract the horizontal and vertical sync pulses that are encoded

on the RGB common-mode voltages by the AD8134.

RECEIVED RED VIDEO

HSYNC

RED CMV

GREEN CMV

BLUE CMV

50

Ω

50

Ω

1k

Ω

1k

Ω

VSYNC

RECEIVED GREEN VIDEO

50

Ω

50

Ω

RECEIVED BLUE VIDEO

50

Ω

50

Ω

Figure 48. Extracting Sync Signals from Received Common-Mode Signals