+

_

THS3001

1 k

Ω

Input

Output

1 k

Ω

20

Ω

THS3001

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 THS3001 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 52. 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.

Figure 52. Driving a Capacitive Load

22

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