It is based on the Johnson-Nyquist noise of a resistor at two different, known temperatures.

In electronics, shot noise and Johnson-Nyquist noise can be measured.

Johnson-Nyquist noise is easily modeled at thermal equilibrium, where all components of the circuit are held at the same temperature.

Resistors create electrical noise, called Johnson-Nyquist noise.

There is an intimate relationship between Johnson-Nyquist noise and Joule heating, explained by the fluctuation-dissipation theorem.

This can be used to derive the formula for Johnson-Nyquist noise and the Dulong-Petit law of solid heat capacities.

In 1928, John B. Johnson discovered and Harry Nyquist explained Johnson-Nyquist noise.

Electronic noise exists in all circuits and devices as a result of thermal noise, also referred to as Johnson-Nyquist noise.

These fluctuations are known as Johnson-Nyquist noise or thermal noise and increase in proportion to the Kelvin temperature of any resistive component.

In addition, shot noise is often less significant as compared with two other noise sources in electronic circuits, flicker noise and Johnson-Nyquist noise.

Operating the pixel via hard reset results in a Johnson-Nyquist noise on the photodiode of or , but prevents image lag, sometimes a desirable tradeoff.

Thermal noise: Johnson-Nyquist noise occurs due to the thermal motions of ions and other charge carriers, producing voltage fluctuations proportional to temperature.

Johnson-Nyquist noise arises from the random thermal motion of electrons, whereas phonon noise arises from the random exchange of phonons.

The power spectral density of the noise is expressed in terms of the temperature (in kelvins) that would produce that level of Johnson-Nyquist noise, thus:

This Johnson-Nyquist noise is a fundamental noise source which depends only upon the temperature and resistance of the resistor, and is predicted by the fluctuation-dissipation theorem.

However, shot noise is temperature and frequency independent, in contrast to Johnson-Nyquist noise, proportional to temperature, and flicker noise, with the spectral density decreasing with the frequency.

Although Johnson-Nyquist noise shares many similarities with phonon noise (e.g. the noise spectral density depends on the temperature and is white at low frequencies), these two noise sources are distinct.

As an engineer at Bell Laboratories, Nyquist did important work on thermal noise ("Johnson-Nyquist noise"), the stability of feedback amplifiers, telegraphy, facsimile, television, and other important communications problems.

Johnson-Nyquist noise (sometimes thermal, Johnson or Nyquist noise) is unavoidable, and generated by the random thermal motion of charge carriers (usually electrons), inside an electrical conductor, which happens regardless of any applied voltage.

Noise considerations dictate that the smallest practical resistance should be used, since the Johnson-Nyquist noise voltage scales with resistance, and any resistor noise in the voltage divider will be impressed upon the amplifier's output.

Headroom can be used either to reduce distortion and audio feedback by keeping signal levels low, or to reduce interference, both from outside sources and from the Johnson-Nyquist noise produced in the equipment, by keeping signal levels high.

In the 1920s, it was discovered that the current through an ideal resistor actually has statistical fluctuations, which depend on temperature, even when voltage and resistance are exactly constant; this fluctuation, now known as Johnson-Nyquist noise, is due to the discrete nature of charge.

The so-called Johnson-Nyquist noise of discrete resistors and capacitors is a type of thermal noise derived from the Boltzmann constant and can be used to determine the noise temperature of a circuit using the Friis formulas for noise.

The standard model of amplifier noise is additive, Gaussian, independent at each pixel and independent of the signal intensity, caused primarily by Johnson-Nyquist noise (thermal noise), including that which comes from the reset noise of capacitors ("kTC noise").

Wideband Gaussian noise comes from many natural sources, such as the thermal vibrations of atoms in conductors (referred to as thermal noise or Johnson-Nyquist noise), shot noise, black body radiation from the earth and other warm objects, and from celestial sources such as the Sun.