Physics:Equivalent noise resistance

In telecommunication, an equivalent noise resistance is a quantitative representation in resistance units of the spectral density of a noise-voltage generator, given by [math]\displaystyle{ R_n = \frac {\pi W_n}{k T_0} }[/math] where [math]\displaystyle{ W_n }[/math] is the spectral density, [math]\displaystyle{ k }[/math] is the Boltzmann constant, [math]\displaystyle{ T_0 }[/math] is the standard noise temperature (290 K), so [math]\displaystyle{ kT_0 = 4.00 \times 10^{-21}\,[Ws] }[/math].

Note: The equivalent noise resistance in terms of the mean-square noise-generator voltage, e², within a frequency increment, Δ f, is given by

[math]\displaystyle{ R_n = \frac{e^2}{4 k T_0\,\Delta f}. }[/math]

See also

• Equivalent input noise
• Effective input noise temperature