What Is Feedback?
Feedback is feeding part of a circuit's output back into its input. This simple idea is the basis of stability, precision and even signal generation in electronics. It comes in two kinds: negative and positive.
What Is Feedback?
When the output signal is measured and returned to the input, the circuit can "watch" and correct its own behavior. This is the most common way to control gain.
Negative Feedback
Negative feedback balances the system by subtracting part of the output from the input. It stabilizes gain, reduces distortion and gives resilience to temperature/manufacturing variation. It's the basis of op-amp circuits.
Positive Feedback
Positive feedback enlarges the effect by adding the output to the input. It produces instability and oscillation, so it's used deliberately in oscillator and comparator (Schmitt trigger) circuits.
| Type | Effect | Use |
|---|---|---|
| Negative | Stabilizing | Amplifier, regulator |
| Positive | Amplifying/oscillating | Oscillator, comparator |
Where Is It Used?
Gain control in amplifiers, holding the output steady in voltage regulators, generating signals in oscillators and control systems (e.g. temperature control) all rely on feedback.
Common Mistakes
- Unwanted positive feedback: incorrectly built negative feedback can turn into oscillation and make the circuit unstable.
- Neglecting the feedback path: feedback components set the gain directly; their values are critical.
- Forgetting delay: at high frequency, delay in the feedback ruins stability.
Frequently Asked Questions
Why does negative feedback lower gain?+
How does an oscillator generate a signal?+
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