A simple quantum expression of the 1/f noise spectrum

of n
+-p diodes operating in the generation-recombination (g-r) mode is obtained that is valid for all bias voltages. It turns out to be quite small. A new quantum 1/f noise effect in diodes operating in the diffusion mode is evaluated; it mimics g-r 1/f noise, but is much larger than it. It should predominate if Umklapp noise is not observable (this has been found to be the case for diffusion in the base region of p
+-n-p or n
+-p-n BJT\´s).