Datasheet

Differential Amplifier
4-10
Example Circuits
4.7 Differential Amplifier
Figure 4–6 shows area 300 equipped with a single operational amplifier
configured as a differential amplifier using a voltage reference and single
power supply.
Basic setup is done by choice of input and feedback resistors. The transfer
function for the circuit as shown is:
V
OUT
V
IN
R 302
R 304
VREF 3
Where
R 302
R 304
R 309
R 308
The TLV431 adjustable precision shunt regulator, configured as shown,
provides a low impedance reference for the circuit at about 1/2 V3+ in a 3 V
system. Another option is to adjust resistors R311 and R310 for the desired
VREF3 voltage. The formula for calculating VREF3 is:
VREF 3 1.24 V
R 311 R 310
R 310
Figure 4–6. Single Operational Amplifier Differential Amplifier with Single Supply Using
Area 300
C304 C303
C306
V3+
V3–
V3+
GND3
V3–
Power Supply Bypass
+
–
7
6
4
3
2
V3+
V3–
R302
C302
R301
C301
R303
R304
R319
R308
R309
R306
C309
C308
3OUT
301–
302–
303+
304+
R311
C
R
A
U302
R310
Voltage Reference
U301
V3+
VREF3 = 1.24 V
R312
+
–
V
in
V
out
= V
in
R302
R304
R302
R304
Jumper
Jumper
TLV431ACDBV5
Jumper 304+ to VREF3
=
R309
R308
()
+ V
REF3
0.1 µF 10 µF
2.2 kΩ
3 FLT
R305
C307
8
3/SD
C305
C310
10 µF