In this article, you will discover What is thermal noise and white noise?, What is the meaning of thermal noise?, What is the difference between thermal noise and shot noise?
What is thermal noise and white noise?
Thermal noise, also known as Johnson-Nyquist noise, arises from the random thermal agitation of electrons in conductors and resistors. This movement generates random voltage fluctuations that are present in all electronic circuits and systems. Thermal noise is characterized by a flat power spectral density across a wide range of frequencies, making it indistinguishable as “white noise” to the human ear because it lacks discernible pitch or frequency.
The significance of thermal noise lies in its fundamental cause: the thermal movement of charge carriers, primarily electrons, in conductive materials. As the temperature increases, the agitation of these electrons increases, leading to higher levels of thermal noise in electronic components. This noise can affect signal quality in communications systems and electronic devices, requiring methods to minimize its impact.
What is the meaning of thermal noise?
The main difference between thermal noise and shot noise lies in their origins and statistical characteristics. Thermal noise is a consequence of thermal agitation and is proportional to temperature. It has a constant power spectral density across all frequencies, contributing evenly to the background sound. Shot noise, on the other hand, results from the discrete nature of the electrical charge and statistical fluctuations as electrons or photons arrive in a detector. Shot noise exhibits a Poisson distribution and is more visible at lower signal levels where the discrete nature of the charge carriers becomes significant.
What is the difference between thermal noise and shot noise?
White noise refers to a type of noise that has a flat power spectral density, meaning that it has equal intensity at all frequencies within a specified bandwidth. Thermal noise is often called white noise because its power spectral density is flat across a wide range of frequencies, just as white light contains all visible wavelengths equally. This flatness makes it useful in various applications where a broad-spectrum noise source is needed for testing, measurement, or random signal generation.
The difference between thermal noise and flicker noise (or 1/f noise) is their frequency characteristics. While thermal noise has a flat power spectral density, flicker noise has a frequency-dependent power spectral density that increases as frequency decreases. Flicker noise is often observed in electronic components and materials due to irregularities or defects that cause variations in conductivity or carrier mobility. Unlike thermal noise, which is predominant at higher frequencies due to thermal agitation, flicker noise becomes more significant at lower frequencies, affecting the performance of sensitive electronic circuits and devices.
We hope this overview of What is thermal noise and white noise? has made things clearer.