AD8091/AD8092

Rev. C | Page 15 of 20

Some circuits use a sync tip clamp to hold the sync tips at a

relatively constant level to lower the amount of dynamic signal

swing required. However, these circuits can have artifacts like

sync tip compression unless they are driven by a source with a

very low output impedance. The AD8091/AD8092 have

adequate signal swing when running on a single 5 V supply to

handle an ac-coupled composite video signal.

The feedback circuit provides unity gain for the dc biasing of

the input and provides a gain of 2 for any signals that are in the

video bandwidth. The output is ac-coupled and terminated to

drive the line.

The capacitor values provide minimum tilt or field time

distortion of the video signal. These values are required for

video that is considered to be studio or broadcast quality.

However, if a lower consumer grade of video, sometimes

referred to as consumer video, is all that is desired, the values

and the cost of the capacitors can be reduced by as much as a

factor of 5 with minimum visible degradation in the picture.

The input to the circuit shown in Figure 36 is a standard

composite (1 V p-p) video signal that has the blanking level at

ground. The input network level shifts the video signal by

means of ac coupling. The noninverting input of the op amp is

biased to half of the supply voltage.

AD8091

5V

+

4.99kΩ

10µF

47µF

+

4.99kΩ

10kΩ

75Ω

1kΩ

1kΩ

75Ω

75Ω

COMPOSITE

VIDEO IN

+

220µF

0.1µF

3

2

4

6

7

1000µF

0.1µF

10µF

+

Figure 36. Single-Supply Composite Video Line Driver