Can You Combat Johnson Noise and Shot Noise in Instrumentation?

[ultimateguy]

I was wondering if someone could give me some ways to combat Johnson noise and shot noise.

Thanks

 

[berkeman]

Sure. What is the context? If it's noise in a sensor, what is the sensor technology? How much amplification do you need? What is the bandwidth and character of the signal that you are amplifying? What kind of back-end processing are you doing of the signal?

 

[ultimateguy]

There isn't really a context. I'm in an instrumentation class, and one of the questions is "Describe the origins of Johnson noise and Shot noise and appropriate countermeasures you can take to deal with them."

I know what they are, but I've been trying for the life of me to find out what the countermeasures are. I don't have them in my class notes and they're not in the textbook.

 

[berkeman]

Well, tell me a little about the effects of temperature and bandwidth on each.

 

[vanesch]

There isn't really a context. I'm in an instrumentation class, and one of the questions is "Describe the origins of Johnson noise and Shot noise and appropriate countermeasures you can take to deal with them."

I know what they are, but I've been trying for the life of me to find out what the countermeasures are. I don't have them in my class notes and they're not in the textbook.

A simple way is to write down the equations giving their spectral density and/or their integrated RMS constribution, and to see what factors lower it. Hint: lowering the temperature might help for Johnson noise. But also other things play a role. Now look at the other quantities in the formulas...