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 hight 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.

 

[alphy]

As a scientist, it is important to understand the different types of noise that can occur in a circuit and how they are characterized. In this case, the two types of noise being discussed are shot noise and avalanche noise.

Shot noise is caused by the random nature of the flow of electrons in a circuit. It is commonly seen in circuits with low current levels and is proportional to the square root of the current. On the other hand, avalanche noise is caused by the breakdown of a semiconductor material under high electric fields. This results in a sudden surge of current and is typically seen in circuits with high voltage levels.

To determine which type of noise is present in your circuit, you can perform measurements and analyze the data. Shot noise can be measured by observing the noise level at different current levels, while avalanche noise can be measured by observing the noise level at different voltage levels. Additionally, the noise level can also be compared to theoretical models for each type of noise to determine which one fits the data better.

It is also worth noting that in some cases, both shot noise and avalanche noise can be present in a circuit simultaneously. In this case, it may be necessary to perform more detailed measurements and analysis to differentiate between the two types of noise.

In conclusion, the best way to determine whether the noise in your circuit is shot noise or avalanche noise is to perform measurements and compare them to theoretical models. It is also important to consider the operating conditions of your circuit to understand which type of noise is more likely to occur.