AD8397

Rev. 0 | Page 12 of 16

CAPACITIVE LOAD DRIVE

When driving capacitive loads, many high speed operational

amplifiers exhibit peaking in their frequency response. In a

gain-of-two circuit, Figure 23 shows that the AD8397 can drive

capacitive loads up to 270 pF with only 3 dB of peaking. For

amplifiers with more limited capacitive load drive, a small series

the capacitive load in order to minimize peaking and ensure

device stability. Figure 24 shows that the use of a 2.2 Ω series

resistor can further extend the capacitive load drive of the

AD8397 out to 470 pF, while keeping the frequency response

peaking to within 3 dB.

5

0

–5

–10

–15

–20

–25

–30

–35

–40

0.01

0.1

1

10

100

FREQUENCY (MHz)

470pF

390pF

330pF

270pF

5

0

–5

–10

–15

–20

–25

–30

–35

–40

0.01

0.1

1

10

100

FREQUENCY (MHz)

220pF

100pF

270pF

150pF

Figure 24. Capacitive Load Peaking with 2.2 Ω Series Resistor

Figure 23. Capacitive Load Peaking Without Series Resistor