Electronics > Beginners
measuring LDO noise with an LNA: shielding questions
(1/1)
exe:
Hi! I want to measure noise of my LDOs (just for fun). So, I want to assemble a low-noise amp that would amplify noise. My understanding is there should be a lot of shielding, preferably the whole measurement setup. Or at least LNA and cables should be shield. And I have a few question how to do it properly, or what are best practices. I have no previous experience with shielding.

To some questions I found answers on the Internet, but I'd like to confirm.

1) Should LNA's shield be earthed? I read conflicting opinions on this (or I misunderstood)
2) Should the shield be connected to LNA's "ground"?
3) Can I use BNC/SMA connectors (with single conductor inside the cable) to connect DUT or I need a cable with two conductors that are shielded? (I've seen both used)
4) What if a shield consists of multiple isolated pieces of foil? If this is not ok, should I connect pieces of the shield in multiple points, or it's enough to connect it in one point?
5) Are shield material and thickness important? Can I use food aluminum foil? Or copper foil be better?
awallin:
see fig6 here
https://www.analog.com/media/en/technical-documentation/application-notes/an83f.pdf
ejeffrey:
What frequency range do you want to measure?  Do you have an estimate of the noise density you expect?  Have you chosen an LNA?  What instrument are you going to use to measure the output of the LNA?

Ordinary coax and BNC/SMA connectors for the appropriate bandwidth should be sufficient for most applications.  Connect the coax shield to the circuit ground.  Or if you are building your own circuit you just connect the regulator output to the LNA input on a PCB.
exe:
I want to measure, say 0.1Hz-10Hz and broadband noise of at least 1MHz. My "lna" is going to be just AD8428BRZ. Noise density... I dunno :). It will be connected to my micsig TO1004 or analog discovery 2.
Zorc:
I'm going to follow this  since I plan on getting into lower noise PSU solutions as well.
Probably end up needing to do some measurement myself to compare them  :)
Navigation
Message Index
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod