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:


  • is the power (in watts)
  • is the total bandwidth (Hz) over which that noise power is measured
  • is the Boltzmann constant (1.381×10−23 J/K, joules per kelvin)
  • is the noise temperature (K)

Thus the noise temperature is proportional to the power spectral density of the noise, . That is the power that would be absorbed from the component or source by a matched load. Noise temperature is generally a function of frequency, unlike that of an ideal resistor which is simply equal to the actual temperature of the resistor at all frequencies.

Read more about Noise Temperature:  Noise Voltage and Current, Application To Communication Systems, Noise Figure, Noise Temperature of An Amplifier Chain

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Noise Temperature of An Amplifier Chain
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Effective Input Noise Temperature
... In telecommunications, effective input noise temperature is the source noise temperature in a two-port network or amplifier that will result in the same output noise power, when ... If F is the noise figure numeric and 290 K the standard noise temperature, then the effective noise temperature is given by T n = 290(F-1) ...
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