Johnson noise

Johnson noise is thermal noise emanating from stochastic electron motion in passive and active electronic components.

Johnson noise is white noise that was detected by American physicist John Bertrand Johnson (1887 - 1970) in the late 1920s during his time at Bell Labs.

Johnson noise occurs on resistors and also on active devices as soon as their temperature is above 0 degrees Kelvin. It is completely statistically distributed noise with a constant noise energy over all frequencies and frequency bands. It is also referred to as Johnson-Nyquist noise.