lämpönoise

Lämpönoise, also known as Johnson-Nyquist noise, is a fundamental electronic noise phenomenon present in all electrical conductors at temperatures above absolute zero. It arises from the random thermal motion of charge carriers, primarily electrons, within the conductor. These electrons are in constant random agitation due to their thermal energy. As they move randomly, they create fluctuating currents, which in turn produce a fluctuating voltage across the conductor.

The intensity of thermal noise is directly proportional to the temperature of the conductor and its resistance. At higher temperatures, the electrons possess more kinetic energy, leading to more vigorous and random motion, and thus a stronger noise signal. Similarly, a higher resistance means a greater impedance to the flow of charge carriers, amplifying the effects of their random movements. The noise is characterized by a wide frequency spectrum, meaning it is present across a broad range of frequencies.

Thermal noise is an unavoidable aspect of electronic systems and can limit the sensitivity of measuring instruments and communication receivers. While it cannot be eliminated, its effects can be minimized through various engineering techniques. These include operating at lower temperatures, using lower resistance components where feasible, and employing noise reduction techniques such as filtering and amplification with low-noise components. Understanding thermal noise is crucial for designing and analyzing sensitive electronic circuits.