Differential Amplifier
3-4 Example Circuits
3.4 Differential Amplifier
Figure 3–3 shows area 100 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:
VOUT VIN R112
R109 VREF1
Where:R112
R109 R102
R103
The TLV431 adjustable precision shunt regulator, configured as shown,
provides a low impedance reference for the circuit at about 1/2 V1+ in a 3-V
system. Another option is to adjust resistors R111 and R113 for the desired
VREF1 voltage. The formula for calculating VREF1 is:
VREF1 1.24 V R111 R113
R113
Figure 3–3.Single Operational Amplifier Differential Amplifier With Single Supply Using
Area 100
C107 C108
C104
V1+
V1–
V1+
GND1
V1–
Power Supply Bypass
+
–
7
6
4
3
2
V1+
V1–
R112
C109
R114 C110
R110
R109
R104
R103
R102
R105
C101
C102
1OUT
101–
102–
103+
104+
R111 C
RAU102
R113
Voltage Reference
U101
V1+
VREF1 = 1.24 V
R108
+
–Vin
Vout = Vin R112
R109
R112
R109
Jumper
Jumper
TLV431ACDBV5
Jumper 104+ to VREF1
=R102
R103
()+ VREF1
0.1 µF 10 µF
2.2 kΩA1 FLT
R106
C103
81/SD
C105
C106
10 µF