Regenerative feedback in a system implies feedback with a positive sign. This means that the feedback signal is added to the input signal, resulting in an amplified output. Let's understand this in more detail:

Introduction to feedback
Feedback is an important concept in control systems. It involves taking a portion of the output signal and feeding it back to the input of the system. This allows the system to regulate its behavior and achieve desired performance.

Positive feedback vs Negative feedback
Feedback can be classified into two types: positive feedback and negative feedback.

Negative feedback: In negative feedback, the feedback signal is subtracted from the input signal. This has a stabilizing effect on the system, as it tends to reduce any deviations between the desired output and the actual output. Negative feedback is commonly used in control systems to improve stability, accuracy, and reduce errors.

Positive feedback: In positive feedback, the feedback signal is added to the input signal. This amplifies the input and can lead to an unstable behavior. Positive feedback is not commonly used in control systems, as it can result in oscillations or uncontrollable behavior.

Regenerative feedback
Regenerative feedback is a specific type of positive feedback where the feedback signal reinforces the input signal, causing an increase in the output. This can lead to continuous amplification and can result in oscillations or instability in the system.

Example of regenerative feedback
An example of regenerative feedback is the Schmitt trigger circuit. This circuit is used to convert a noisy or distorted input signal into a clean digital signal. It uses positive feedback to create hysteresis, which helps in noise immunity and signal conditioning.

The Schmitt trigger circuit consists of an operational amplifier and positive feedback resistors. When the input signal crosses a certain threshold, the output changes state, and the positive feedback reinforces this change, causing a rapid transition in the output. This positive feedback helps in noise rejection and provides a sharp output transition.

Conclusion
In summary, regenerative feedback implies feedback with a positive sign, where the feedback signal is added to the input signal. This can lead to amplification and instability in the system. Negative feedback, on the other hand, involves subtracting the feedback signal from the input signal and is commonly used to improve stability and accuracy in control systems.