The Quest for Quiet

I ran across an interesting white paper from Analog Devices. It describes the issues that Analog Devices engineers had with building an accurate method to measure very low levels of analog noise. Such a meter is needed to measure noise on their LT3042 voltage regulator that has noise in the low micro-volt range.

I learned something about low noise circuit design. In particular, I found their filtering scheme interesting, as well as their discussion on component selection. I also love their shielding approach right down to the cookie tin.

For anyone wanting to build a really sensitive noise meter, they provide a full schematic and discuss the components enough that it would be easy to recreate their meter.

https://www.analog.com/en/resources/app-notes/an-159.html

 

Note the use of three different materials for shielding, mu-metal, copper Faraday cage and steel.
Observe also the use of the ancient HP 400E millivoltmeter, similar to the Leader LMV-182A I use.

 

For all you 0.00000X freaks: