Negative And positive Feedback

In summary, combining negative and positive feedback in one opAmp can lead to a lightly damped system with oscillatory behavior, especially if the positive feedback is frequency-dependent. If the op-amp is ideal, the system will behave similarly to having less negative feedback.
  • #1
khotsofalang
21
0
What happens if you combine both negative and positive feedback in one opAmp?

assuming you only have unity gain in the negative configuration and no capacitors? I reckon
adding capacitors would add some oscillatory behavior but would that be the case if both configurations are made only of resistors? why?
 
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  • #2
khotsofalang said:
What happens if you combine both negative and positive feedback in one opAmp?

assuming you only have unity gain in the negative configuration and no capacitors? I reckon
adding capacitors would add some oscillatory behavior but would that be the case if both configurations are made only of resistors? why?
The positive feedback will cancel out some of the negative feedback. Usually you would make the positive feedback frequency-dependent to tailor the frequency response of the overall system. If the positive feedback comes close to cancelling the negative feedback at some frequency, then the system will be lightly damped and show an oscillatory response to a step input.

If the op-amp were ideal, then both purely resistive networks would be equivalent to just less negative feedback.
 

1. What is negative feedback and how does it work?

Negative feedback is a regulatory mechanism in which the output of a system or process is used to decrease the activity of the system or process. This helps to maintain a stable state or balance within the system. For example, in the human body, negative feedback is responsible for maintaining a constant body temperature. When the body temperature rises, negative feedback activates a response to decrease it, such as sweating. This helps to prevent overheating and maintain a stable body temperature.

2. What is positive feedback and how does it differ from negative feedback?

Positive feedback is a regulatory mechanism in which the output of a system or process is used to increase the activity of the system or process. This results in a self-amplifying cycle, where the initial output leads to further increases in output. Unlike negative feedback, which aims to maintain a stable state, positive feedback can lead to instability and exponential growth. An example of positive feedback is the release of oxytocin during childbirth, which triggers contractions that lead to more oxytocin release and stronger contractions.

3. How is negative feedback involved in homeostasis?

Homeostasis is the process by which the body maintains a stable internal environment. Negative feedback plays a crucial role in this process by detecting and responding to changes in the body's internal conditions. If the body temperature, blood glucose levels, or hormone levels deviate from their set point, negative feedback mechanisms are activated to bring them back to the desired range. This helps to maintain a stable and healthy internal environment.

4. Can negative feedback be harmful?

While negative feedback is essential for maintaining homeostasis, it can sometimes have unintended consequences. For example, in some cases, negative feedback can lead to a decrease in the production of necessary hormones or enzymes, which can disrupt normal bodily functions. Additionally, negative feedback can also create a delay in response time, which can be problematic in emergency situations. However, overall, negative feedback is a crucial regulatory mechanism that helps to keep our bodies functioning optimally.

5. How is positive feedback used in technology and engineering?

In technology and engineering, positive feedback is often used to amplify or increase the output of a system. For example, in audio equipment, positive feedback is used to amplify and improve the quality of sound signals. In electronic circuits, positive feedback can also be used to create oscillators, which are used in devices such as radios and clocks. Additionally, positive feedback is used in control systems to quickly respond to changes in a system and maintain stability, similar to how it works in the human body.

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