Electronic – Is the avalanche noise “random?”

amplifierencryptionpn-junctionrandom number

I'm working on a hardware random number generator based on the below design. It uses two reverse P-N junctions to create avalanche noise.

I was looking at the circuit with my oscilloscope, and I found that the unamplified noise from the two junctions seems HIGHLY correlated. (Enough entropy, however, seems to be added/amplified by the rest of the circuit so the bitstreams appear uncorrelated.)

So, is avalanche noise not the self-contained random process I thought it was, but something highly sensitive to external forces such as minor fluctuations on the rail? Or, have I’ve built a system that is amplifying something other than avalanche noise?

Duel Reverse P-N Junction circuit
enter image description here

Best Answer

It's your scope or your power supply. Try connecting both scope channels to 0V and see how the signals correlate and, in fact how much residual noise your scope channels have.

Next connect both channels to the 12V and see what happens.

Rest assured that there will be no correlation in the noises from two different semiconductor sources other than that caused by power supply noise (common to both).