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thermal noise

Thermal noise is caused by statistical fluctuations of the charge carriers in all electrically conductive materials. These irregularities are caused by the temperature movement of the charge carriers and generate a noise voltage at conductors and resistors

. Since thermal noise contains all frequencies and has a continuous power spectrum, the spectral noise density is the same regardless of the frequency range. This is also known as white noise

.

Calculating Thermal Noise

Calculating Thermal Noise

For example, the noise energy between 5 kHz and 5.1 kHz is the same as that between 100 kHz and 100.1 kHz because in both cases the frequency band is 100 Hz.

However, the noise energy depends on the electrical resistance and increases with increasing resistance values. Thermal noise or white noise was demonstrated by the American physicist Johnson and is also known as Johnson noise.

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Englisch: thermal noise
Updated at: 12.12.2007
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