See this article on shot noise.A common way of getting a noise source is to use a back biased NPN junction, but the RMS output varies greatly from transistor to transistor. Does the RMS value depend on any other measurable/predictable value (beta, maybe?)
I doubt the semiconductor processing and testing for those devices controls for that characteristic, and I don't think the noise level can be inferred from anything else on the datasheet; to get repeatable noise voltages I think you'd have to resort to specialized components like noise diodes.OK, late reply here - thanks for the help, shot noise and advice on measuring noise received, but what I want to do is to say - if i buy 100 of this particular zener diode (or transistor and use it back biased) what range of noise voltage can I expect between them? They are all different, if I want a type in which the noise varies very little from diode to diode, how do i know which ones to choose? There is no measure of it on the datasheet, so can I infer it from some other measurement that is on the datasheet?
This app note from Linear Tech shows one approach to doing that, in Fig. 17.the noise AGC is - i think - an improvement on the trimmer
by Aaron Carman
by Aaron Carman
by Aaron Carman
by Jake Hertz