Datasheet

V
IN
−
+
−
+
DV
DD
V
OCM
AV
SS
AV
DD
A
IN2
A
IN1
V
DD
V
ref
5 V
V
CC
0.1 µF
R
PU
R
PU
THS1206
V
CC
R
f
R
g
V
CC
R
f
R
g
V
P
V
OUT
V
OUT
R
PU
+
V
P
– V
CC
ǒ
V
IN
– V
P
Ǔ
1
RG
)
ǒ
V
OUT
– V
P
Ǔ
1
RF
THS413x
Output
Output
20 Ω
20 Ω
390 Ω
390 Ω
390 Ω
390 Ω
THS4130
THS4131
www.ti.com SLOS318H –MAY 2000– REVISED MAY 2011
Some single-supply applications may require the input voltage to exceed the common-mode input voltage range.
In such cases, the circuit configuration of Figure 32 is suggested to bring the common-mode input voltage within
the specifications of the amplifier.
Figure 32. Circuit With Improved Common-Mode Input Voltage
Equation 2 is used to calculate R
PU
:
(2)
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 THS413x 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 decreases the device 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 33. A minimum value of 20 Ω should work well for most applications. For
example, in 50-Ω transmission systems, setting the series resistor value to 50 Ω both isolates any capacitance
loading and provides the proper line impedance matching at the source end.
Figure 33. Driving a Capacitive Load
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