ADA4896-2 AD [Analog Devices], ADA4896-2 Datasheet - Page 20

• Manufacturer Part Number: ADA4896-2
• Description: 1 nV/?Hz, Low Power, Rail-to-Rail Output Amplifiers
• Manufacturer: AD [Analog Devices]

ADA4896-2/ADA4897-1
CAPACITANCE DRIVE
Capacitance at the output of an amplifier creates a delay
within the feedback path that, if within the bandwidth of
the loop, can create excessive ringing and oscillation. The
ADA4897-1/ADA4896-2
of +2, as demonstrated in Figure 8.
show the most peaking at a gain
Figure 48. Using a Snub Resistor to Reduce Peaking Due to Output Capacitive Load
–1
–2
–3
–4
–5
100k
3
2
1
0
V
V
G = +2
V
S
OUT
IN
R
= 5V
SNUB
= 200mV p-p
249Ω
R
= 100Ω
1
ADA4896-2
249Ω
Rev. 0 | Page 20 of 28
1M
R
2
FREQUENCY (Hz)
R
SNUB
= 50Ω
R
SNUB
R
Putting a small snub resistor (R
output and the capacitive load mitigates the problem. Figure 48
shows the effect of using a snub resistor (R
peaking for the worst-case frequency response (gain of +2).
Using R
trade-off that the closed-loop gain is reduced by 0.8 dB due to
attenuation at the output. R
100 Ω to maintain an acceptable level of peaking and closed-
loop gain, as shown in Figure 48.
SNUB
R
1kΩ
V
L
10M
OUT
= 0Ω
C
39pF
L
SNUB
= 100 Ω eliminates the peaking entirely, with the
100M
SNUB
SNUB
can be adjusted from 0 Ω to
) in series with the amplifier
SNUB
) on reducing the