"Chapter 1 - The Op Amp's Place in the World" - HTL Wien 10

|m| 5.56 R F
R G
R F 5.56R G
Single-Supply Op Amp Design Techniques
Simultaneous Equations
(4–51)
(4–52)
Let RG = 10 kΩ, and then RF = 56.6 kΩ, which is not a standard 5% value, hence RF is
selected as 56 kΩ.
b V (4–53)
CCRF RG RG R1 1056 10
R1 R2 10 R1 R1 R2 R 2 66–0.4444
0.4444 R 1 147.64R 1
The final equation for the example is given below
V OUT 5.56V IN 0.444
(4–54)
(4–55)
Select R 1 = 2 kΩ and R 2 = 295.28 kΩ. Since 295.28 kΩ is not a standard 5% resistor value,
R 1 is selected as 300 kΩ. The difference between the selected and calculated value of
R 1 has a nearly insignificant effect on b. The final circuit is shown in Figure 4–17, and the
measured transfer curve for this circuit is shown in Figure 4–18.
VIN
VCC = 10 V
R2
2 kΩ
D1
Figure 4–17. Case 3 Example Circuit
RG
10 k Ω
R1
300 kΩ
VCC = 10 V
0.01 µF
_
+
0.01 µF
RF
56 kΩ
RL
10 kΩ
VOUT
4-17