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 $$R_n = \frac {\pi W_n}{k T_0} $$ where $$W_n$$ is the spectral density, $$k$$ is the Boltzmann constant, $$T_0$$ is the standard noise temperature (290 K), so $$kT_0 = 4.00 \times 10^{-21}\,[Ws]$$.

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


 * $$R_n = \frac{e^2}{4 k T_0\,\Delta f}.$$