Datasheet

5V
Single-Ended
Input
R
F
R
F
R
G
R
G
THS4511
Differential
Output
V
OUT+
V
OUT–
+
–
–
+
R
F
V
OUT+
V
OUT–
5V
V
IN–
R
F
R
G
R
G
V
IN+
THS4511
Differential
Input
Differential
Output
+
–
–
+
÷
÷
ø
ö
ç
ç
è
æ
+
´+
÷
÷
ø
ö
ç
ç
è
æ
+
´=
-+
FG
F
IN
FG
G
OUT
IC
RR
R
V
RR
R
V
V
THS4511
www.ti.com SLOS471E –SEPTEMBER 2005–REVISED NOVEMBER 2009
APPLICATION INFORMATION
APPLICATIONS
The following circuits show application information for
the THS4511. For simplicity, power-supply
decoupling capacitors are not shown in these
diagrams. For more detail on the use and operation
of fully-differential operational amplifiers refer to
application report Fully-Differential Amplifiers
(SLOA054).
Differential Input to Differential Output Amplifier
The THS4511 is a fully-differential operational
amplifier, and can be used to amplify differential input
signals to differential output signals. A basic block
Figure 44. Single-Ended Input to Differential
diagram of the circuit is shown in Figure 43 (CM input
Output Amplifier
not shown). The gain of the circuit is set by R
F
divided by R
G
.
Input Common-Mode Voltage Range
The input common-model voltage of a fully-differential
operational amplifier is the voltage at the (+) and (–)
input pins of the operational amplifier.
It is important to not violate the input common-mode
voltage range (V
ICR
) of the operational amplifier.
Assuming the operational amplifier is in linear
operation the voltage across the input pins is only a
few millivolts at most. So finding the voltage at one
input pin determines the input common-mode voltage
of the operational amplifier.
Treating the negative input as a summing node, the
voltage is given by Equation 1:
Figure 43. Differential Input to Differential Output
(1)
Amplifier
To determine the V
ICR
of the operational amplifier, the
voltage at the negative input is evaluated at the
Depending on the source and load, input and output
extremes of V
OUT+
.
termination can be accomplished by adding R
IT
and
R
O
.
As the gain of the operational amplifier increases, the
input common-mode voltage becomes closer and
Single-Ended Input to Differential Output
closer to the input common-mode voltage of the
Amplifier
source.
The THS4511 can be used to amplify and convert
single-ended input signals to differential output
signals. A basic block diagram of the circuit is shown
in Figure 44 (CM input not shown). The gain of the
circuit is again set by R
F
divided by R
G
.
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