Lämpökohinana

Lämpökohinana, also known as thermal noise or Johnson-Nyquist noise, is a random electrical signal found in electrical conductors and electronic components. It arises from the random thermal motion of charge carriers, such as electrons, within a conductor. As these charge carriers move randomly, their motion creates fluctuating current and voltage signals, which are perceived as noise.

The magnitude of thermal noise is directly proportional to the absolute temperature of the conductor and the bandwidth of the measurement. At higher temperatures, the charge carriers have more kinetic energy, leading to greater random motion and thus increased noise. Similarly, a wider bandwidth allows for the detection of a larger range of noise frequencies, resulting in a higher measured noise power.

This phenomenon is fundamental to all electronic circuits and devices that involve electrical conduction. While it is an inherent property of conductors, it can be a limiting factor in the performance of sensitive electronic instruments, such as amplifiers and detectors, where the noise signal can mask weak desired signals.

The mathematical description of thermal noise power is given by the Johnson-Nyquist formula. This formula relates the noise power spectral density to Boltzmann's constant, the absolute temperature, and the resistance of the conductor. Understanding and accounting for thermal noise is crucial in the design and analysis of electronic systems to ensure optimal performance and signal integrity.