AD828

REV. B

–11–

3

2

1

1/2

AD828

1/2

AD828

510

2

3

100FT

RG59A/U

1

1/2

AD828

5

6

7

6

5

1/2

AD828

7

510

510

536

510

510

536

510

Full-Duplex Transmission

Superior load handling capability (50 mA min/amp), high band-

width, wide supply voltage range and excellent crosstalk

rejection makes the AD828 an ideal choice even for the most

demanding high speed transmission applications.

The schematic below shows a pair of AD828s configured to

drive 100 feet of coaxial cable in a full-duplex fashion.

Two different NTSC video signals are simultaneously applied at

This situation is illustrated in Figures 43 and 44. These pictures

clearly show that each input signal appears undisturbed at its

output, while the unwanted signal is eliminated at either receiver.

The transmitters operate as followers, while the receivers’ gain is

chosen to take full advantage of the AD828’s unparalleled CMRR.

(In practice this gain is adjusted slightly from its theoretical

chosen to match the characteristic impedance of the cable

employed.

Finally, although a coaxial cable was used, the same topology

applies unmodified to a variety of cables (such, as twisted pairs

often used in telephony).

10

90

0%

100

500mV

500mV

10µs

Figure 43. A Transmission/B Reception

Figure 42. Bidirectional Transmission CKT

10

90

0%

100

500mV

500mV

10µs

Figure 44. B Transmission/A Reception

A High Performance Video Line Driver

The buffer circuit shown in Figure 45 will drive a back-

terminated 75

Ω video line to standard video levels (1 V p-p)

with 0.1 dB gain flatness to 40 MHz with only 0.05

° and 0.01%

differential phase and gain at the 3.58 MHz NTSC subcarrier

frequency. This level of performance, which meets the require-

ments for high-definition video displays and test equipment, is

achieved using only 7 mA quiescent current/amplifier.

3

2

1

1/2

AD828

8

0.1 F

4

+15V

–15V

75

75

1k

1.0 F

0.1 F

1.0 F

1k

75

75

Figure 45. Video Line Driver