This op amp does not have gain?

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The discussion centers on the behavior of an op amp in an inverting configuration, emphasizing that it should not exhibit gain in DC or AC circuits due to the coupling capacitor blocking DC and the need for a capacitor in the feedback loop for AC gain. It is noted that the circuit, particularly a differentiator, may only function correctly under ideal conditions, as real-world applications often lead to instability. A capacitor in the feedback path is clarified to reduce overall AC gain rather than increase it, highlighting the inverse relationship between feedback and forward gain. Participants suggest further study on feedback stability and the frequency-dependent behavior of circuit components. Understanding these concepts is crucial for effectively working with op amps in practical scenarios.
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this op amp doe snot have again in AC or DC
Had this as a question from a class mate. This op amp should not have any gain in the DC or AC circuit. The coupling cap blocks DC and has no reference to get gain, while the AC needs a cap in the feedback loop to get gain. Is that correct? Oh, this is supposed to be in the inverting configuration.

1628515130391.png
 
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Welcome to PF. :smile:

It looks fine to me...

1628516050512.png

https://www.electronics-tutorials.ws/opamp/opamp_7.html
 
Thanks!
 
EENSEEY, you should realize that the shown circuit (differentiator) will work under ideal conditions only (ideal opamp with a gain that is not frequency-dependent).
Under real conditions the circuit will be unstable.
Question: Why do you think that a cap is required in the feedback path to get gain?
 
Yes, what @LvW said. This is actually a very difficult circuit to make work without oscillation. You'll learn more about that later when you've studied more about feedback stability, bode plots, and and the bandwidth limitations of real world amplifiers.

A cap in the feedback path will reduce the overall AC gain, not increase it. More feedback makes less forward gain.

Your next step should be to study about feedback in simple amplifiers, and the frequency dependent behavior of the basic components: inductors, capacitors and resistors.
 
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