What Is the Role of an Integrator in a Differential Amplifier's Feedback Path?

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Discussion Overview

The discussion revolves around the role of an integrator in the feedback path of a differential amplifier circuit. Participants explore its potential functions, including frequency gain discrimination and filtering effects, while considering the implications of multiple feedback paths and the circuit's application context.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • Some participants propose that the integrator in the feedback path could serve a function related to frequency gain discrimination.
  • Others suggest that the integrator might result in a differentiation transfer function, depending on the overall circuit configuration.
  • A participant mentions that the integrator could act as a crude filter.
  • One participant describes an application where the integrator generates a ramp that modulates a lower frequency sine wave, although this is later identified as a failure mode of the circuit.
  • Another participant asserts that the integrator in the feedback loop functions primarily as a low pass filter.
  • There is a request for more details, such as circuit diagrams, to better understand the circuit's behavior and the role of the integrator.
  • Concerns are raised about the nature of the inquiry, with a suggestion that it resembles a homework question requiring more effort from the original poster.

Areas of Agreement / Disagreement

Participants express differing views on the function of the integrator in the feedback path, with no consensus reached on its primary role or the implications of its presence in the circuit.

Contextual Notes

Participants note the importance of circuit diagrams and detailed explanations to facilitate understanding, indicating that assumptions about the circuit's operation may vary among contributors.

Who May Find This Useful

Individuals interested in differential amplifier design, feedback systems, and circuit analysis may find this discussion relevant.

matheinste
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Hello all

I have come across a circuit of a standard differential amplifier with an integrator in one of the feedback paths. I have no idea what its function is. I suppose some sort of frequency gain discrimination Any ideas?

Matheinste
 
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matheinste said:
Hello all

I have come across a circuit of a standard differential amplifier with an integrator in one of the feedback paths. I have no idea what its function is. I suppose some sort of frequency gain discrimination Any ideas?

Matheinste

Seems like an integrator in the feedback path would result in a differentiation transfer function. Are there multiple feedback paths? Can you post a copy of the circuit and put its application into context?


EDIT -- Duh, I just noticed that you said there were multiple feedback paths. I need to read posts a bit slower, it appears. So my guess is that the overall transfer function needed a differentiator term on that variable that is being fed back through the integrator, and different transfer functions on the other feedback paths. Sounds like an interesting circuit -- can you post more details?
 
Last edited:
It might just be a crude filter.
 
Hello all.

Thanks for your replies.

It seems that in the application in which this circuit is used a ramp is generated by the integrator which modulates a sine wave applied to the input. This sine wave is of a very much lower frequency than the repetition rate of the ramp. After further analogue and software processing, the fequency and amplitude of the input sinewave is reovered. Why it is done this way i have still to find out.

Matheinste.
 
Hello all.

I have now found out that the operation described in my last post is a failure mode and not how the circuit should behave.

The integrator in the feedback loop is just a low pass filter.

What is he advantage of the filter being in the feedback loop.

Matheinste.
 
matheinste said:
Hello all.

I have now found out that the operation described in my last post is a failure mode and not how the circuit should behave.

The integrator in the feedback loop is just a low pass filter.

What is he advantage of the filter being in the feedback loop.

Matheinste.

This is starting to sound like a homework/coursework question. If it is, I can move it to the Homework Help forums here at the PF.

matheinste, whether this thread stays here in EE or gets moved to the Homework Help forums here on the PF, we require you to do the bulk of the work for your posts. You will need to post circuit diagrams and supply your impressions and explanations of the diagrams before we help you. We do not help you cheat here on the PF -- we are all about learning and figuring things out. Show us what you are asking about, and show us your work.
 
Hello berkeman

While i may be guilty of laziness, I am 60 years old and stopped doing homework 40 years ago.

Thanks to everyone for their replies.

Matheinste.
 
matheinste said:
Hello berkeman

While i may be guilty of laziness, I am 60 years old and stopped doing homework 40 years ago.

Thanks to everyone for their replies.

Matheinste.

I didn't say anything about laziness...didn't mean to imply that at all. I was just asking for more information and input from you. It's pretty hard to try to answer your questions without a full circuit diagram showing the parts that you are wondering about.
 

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