Youtube link : https://youtu.be/lsZZb1K_Crw
Figure 1
Figure 2
Now the question is why we are using Op amp ? What is the benefit of using Op amp here?
We have observed that
1. For figure 1 circuit, the cut-in voltage make a visible change in the output voltage,but for the figure 2 circuit, the change in the output is negligible due to high gain of op amp.
2. We can amplify the voltage using feedback (figure 4 circuit).
3. From Bode plot, we observed that the phase response and gain are quite smooth for figure 2 circuit.
You might observe that when we use R2 and R3 in figure 2 circuit, the disruptive change in bode plot decreases. Here a question arises why this happens.
It is quite true that the level of noise decreases in case of negative feedback. Here another question arises whether there is any relation between feedback resistance and noise decrement and if so, what is relation between them? It will be discussed in another video.
Figure 3: Frequency response of Circuit of Fig.2
Figure 4: Modified version of circuit of Figure 2
Figure 5: Frequency response of Circuit of Fig.4
Additional materials :
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