negativefeedback

Negative feedback is a regulatory mechanism in which a system’s output acts to reduce or counteract deviations from a set point, thereby stabilizing the variable. The feedback is called negative because it opposes the initial change. It typically involves sensing the output, comparing it with a reference, and activating a control process to dampen the variation.

In biology, negative feedback maintains homeostasis. For example, body temperature is kept near a constant value through responses such as sweating or shivering; blood glucose levels are regulated by insulin and glucagon; osmoregulation involves hormones like antidiuretic hormone. These loops help keep internal conditions within narrow limits despite external fluctuations.

In engineering and electronics, negative feedback is used to improve system performance. It reduces sensitivity to disturbances, stabilizes control systems, and enhances linearity and bandwidth in amplifiers. A portion of the output is fed back to the input in opposition to the input signal. Designers analyze loop gain and phase margin to ensure stability; improper implementation can lead to oscillations or instability.

Negative feedback is distinct from positive feedback, which amplifies deviations and can drive systems toward extremes or runaway states. Real-world systems often use a combination of feedback types to achieve desired behavior in a robust and controllable manner.