THS6007

DUAL DIFFERENTIAL LINE DRIVERS AND LOW-POWER RECEIVERS

SLOS334– DECEMBER 2000

33

POST OFFICE BOX 655303

APPLICATION INFORMATION

general configurations (continued)

THS6007 driver amplifiers can also be used as very good video distribution amplifiers. One characteristic of

distribution amplifiers is the fact that the differential phase (DP) and the differential gain (DG) are compromised

as the number of lines increases and the closed-loop gain increases. Be sure to use termination resistors

throughout the distribution system to minimize reflections and capacitive loading.

+

–

620

Ω

620

Ω

75

Ω

75

Ω

75

Ω

75

Ω

75

Ω

N Lines

VO1

VON

THS6007

75

Ω Transmission Line

VI

Figure 90. Video Distribution Amplifier Application

driving a capacitive load

Driving capacitive loads with high performance amplifiers is not a problem as long as certain precautions are

taken. The first is to realize that the THS6007 has been internally compensated to maximize its bandwidth and

slew rate performance. When the amplifier is compensated in this manner, capacitive loading directly on the

output will decrease the device’s phase margin leading to high frequency ringing or oscillations. Therefore, for

capacitive loads of greater than 10 pF, it is recommended that a resistor be placed in series with the output of

the amplifier, as shown in Figure 91. A minimum value of 20

Ω should work well for most applications. For

example, in 75-

Ω transmission systems, setting the series resistor value to 75 Ω both isolates any capacitance

loading and provides the proper line impedance matching at the source end.

+

_

THS6007

Receiver

CLOAD

1.3 k

Ω

Input

Output

1.3 k

Ω

20

Ω

Figure 91. Driving a Capacitive Load