Below you will find circuits with an ideal operational amplifier, which are similar to the non-inverting amplifier and whose voltage gain $A_V$ must be determined.
Assumptions
Exercises
Enter the voltage gain $A_\rm V$ for each circuit. A detailed calculation as before is not necessary.
For Figure 7, indicate how the voltage gain can be determined.
Generalize with the following justifications:
How has a short circuit of the two OPV inputs must be taken into account?
How do resistances have to be considered in the following cases:
with one terminal (so „one connector“) directly and exclusively on an OPV input,
with both terminals each directly connected to an OPV input.
In which circuits do resistors $R_3$ and $R_4$ represent an unloaded voltage divider?
To approach the problems, you should try to use the knowledge from the inverting amplifier. It can be useful to simulate the circuits via Falstad-Circuit or Tina TI. In the first two circuits, tips can be seen under the illustration as support.
Important: As always in your studies, you should try to generalize the knowledge gained from the task.
Tipps
How big is the current flow into the inverting and non-inverting input of an ideal operational amplifier? So what voltage drop would there be across a resistor whose one connection only leads to one input of the operational amplifier ($R_3$)?
The operational amplifier always tries to output as much current at the output that the required minimum voltage $U_\rm D$ results between the inverting and non-inverting input. How high can $U_\rm D$ be assumed? Can this voltage also be built up via a resistor ($R_4$)?
Can different resistors (e.g. because they are between the same nodes) be combined?
Abb. 1
Hints
How high is the current flow into the inverting and non-inverting input of an ideal operational amplifier? What voltage drop would there be across a resistor whose one connection only leads to one input of the operational amplifier? ($R_3$)?
The operational amplifier always tries to output enough current at the output so that the required minimum voltage is between the inverting and non-inverting input $U_\rm D$ results. How big can $U_\rm D$ be accepted? Can this voltage also via a resistor ($R_4$) being constructed?
Abb. 2
Hints
How much current must flow through $R_4 = R$ so that the expected voltage $U_4$ results?
How much current must flow through $R_2 = 2 \cdot R$ fließen?
How much current must flow through $R_1 = R$? How high is the voltage at $R_1$?
Abb. 3
Abb. 4
Abb. 5
Abb. 6
Abb. 7
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Abb. 9