An operational amplifier with a finite gain
Introduction
This example shows the operation of an operational amplifier with a finite gain.
Description of the model
The operational amplifier block in the basic physics modeling library Engee simulates an ideal case in which the gain is infinite, the input impedance is infinite, and the output impedance is zero. The finite gain operational amplifier unit in this example has an open-loop gain of 1e5, an input impedance of 100 kohms and an output impedance of 10 ohms.
As a result, the gain for this amplifier circuit is slightly lower than the gain that can be calculated analytically if we assume that the gain of the operational amplifier is infinite.
Simulation
Download and execute the assembled model.
Путь_примера = "$(@__DIR__)";
Имя_модели = "finite_gain_op_amp";
Путь_модели = joinpath(Путь_примера, Имя_модели*".engee")
if Имя_модели ∉ getfield.(engee.get_all_models(), :name)
engee.load(Путь_модели);
end
модель = engee.run(Имя_модели);
Simulation results
We will get the required values from the simulation results.
t = модель["Vin"].time;
Vin = модель["Vin"].value;
Vout = модель["Vout"].value;
k_fin = модель["k_fin"].value;
k_fin = k_fin[length(k_fin)];
k_inf = модель["k_inf"].value;
k_inf = k_inf[length(k_inf)];
Let's plot the input and output voltages.:
using Plots
gr()
plot(t, [Vin, Vout]; ylabel = "Напряжение, В", label = ["V вх" "V вых"])
Let's estimate the values of the gain coefficients:
print("Коэффициент усиления идеального ОУ: ", k_inf, "\n")
print("Коэффициент усиления идеального ОУ: ", round(k_fin; digits = 2))
As can be seen, for an op-amp with a finite gain, its value turned out to be lower than the gain of an ideal op-amp.
Conclusion
In the considered example, an operational amplifier circuit with a finite gain is assembled and modeled.