At its most fundamental level, feedback in an electronic system is the process of extracting a portion of the output signal and returning it to the input, where it combines with the original input signal. This seemingly simple closed-loop interaction forms the backbone of countless sophisticated electronic circuits, enabling precise control, enhanced performance, and sometimes, intentional signal generation.

The core components that constitute a general feedback system are:
● Basic Amplifier (Forward Path): This is the primary amplification stage, possessing an open-loop gain, typically denoted by A. Its function is to amplify the effective input signal.
● Feedback Network (Feedback Path): This circuit samples a specific characteristic of the output signal (e.g., voltage or current) and transforms it into a form suitable for injection back into the input summing junction. This network is generally composed of passive components (resistors, capacitors, inductors) to ensure its stability and predictability. The feedback factor, βF, represents the fraction or characteristic of the output signal that is returned to the input.
● Summing/Comparison Network: This is the point where the original input signal and the feedback signal are combined. The nature of this combination (addition or subtraction) dictates whether the feedback is positive or negative.
● Load: The external circuit or component connected to the amplifier's output, which the amplifier is designed to drive.

Positive feedback occurs when the feedback signal, upon returning to the input, is in phase with (or adds to) the original input signal. This means the feedback actively reinforces the input, leading to a cumulative effect.
● Mechanism of Operation: Consider a small initial change in the input signal. This change is amplified by the basic amplifier, producing a corresponding change at the output. With positive feedback, a portion of this output change is fed back to the input in such a way that it augments the original input change.

● Advantages of Positive Feedback:
- Oscillation Generation: The most significant and widely utilized application of positive feedback is in the design of oscillators.
- Increased Gain: While typically avoided in amplifiers, positive feedback can theoretically lead to extremely high gain.
- Improved Selectivity: In resonant circuits, positive feedback can effectively increase the Q-factor.

● Disadvantages of Positive Feedback:
- Instability: Unintentional positive feedback can lead to unwanted oscillations.
- Increased Distortion: Any non-linearity is reinforced, degrading signal quality.
- Reduced Bandwidth: Tends to narrow the amplifier's operating frequency range.

Negative feedback occurs when the feedback signal, upon returning to the input, is 180 degrees out of phase with (or subtracts from) the original input signal. This means the feedback actively opposes the input, leading to a stabilizing and self-correcting effect.
● Mechanism of Operation: Consider an increase in the input signal. This is amplified, causing an increase at the output. With negative feedback, a portion of this increased output is fed back to the input in such a way that it reduces the effective input signal.

● Advantages of Negative Feedback:
- Improved Gain Stability: Reduces sensitivity to variations in open-loop gain.
- Reduced Non-linear Distortion: Linearizes the amplifier's response.
- Increased Bandwidth: Extends the useful operating frequency range.
- Reduced Noise: Effectively cancels internal noise.

● Disadvantages of Negative Feedback:
- Reduced Overall Gain: Needed to achieve desired closed-loop gain.
- Potential for Instability: Might turn into positive feedback at higher frequencies.
- Increased Circuit Complexity: Requires additional components for feedback.