Noise temperature
In electronics, noise temperature is one way of expressing the level of available noise power introduced by a component or source. 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: P N B = k B T {\displaystyle {\frac {P_{\text{N}}}{B}}=k_{\text{B}}T} where: P N {\displaystyle P_{\text{N}}} is the noise power (in W, watts) B {\displaystyle B} is the total bandwidth (Hz, hertz) over which that noise power is measured k B {\displaystyle k_{\text{B}}} is the Boltzmann constant (1.381×10−23 J/K, joules per kelvin) T {\displaystyle T} is the noise temperature (K, kelvin) Thus the noise temperature is proportional to the power spectral density of the noise, P N / B {\displaystyle P_{\text{N}}/B} .