Is It Shot Noise or Avalanche Noise in Your Circuit?

[Mr Peanut]

I frequently see the following circuit being used as a noise generator:

... where the transistors are basic npn bipolar transistors.

Some authors attribute the noise to shot noise while others say it is avalanche noise.

How do I determine which is correct?

 

[Mr Peanut]

For example:
http://sanchezdavid.files.wordpress.com/2010/08/circuits-ii-term-paper-final.pdf
Attributes it to shot noise.

Here's on that says it avalanche noise: http://web.jfet.org/hw-rng.html

 

[NascentOxygen]

I have no idea. But wonder whether dunking it in liquid nitrogen would reveal anything useful?

 

[f95toli]

Couldn't it be argued that avalanche noise is a type of shot noise?
The "definition" of shot noise is that it is noise caused by the fact the the current/signal is carried by discrete carriers; and from what I understand this is also the case for avalanche noise.

That said, I suspect it will depend on the details of the circuit, avanches occur at height field gradients and whether or not this is the case will probably depend on the exact type of transistor you are using. You will probably also always have quite a bit of shot noise.