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Atta Rehman , 03-19-2025, 08:48 AM

Hi @Robert Feranec . @QDrives , @Phil

Document attached with figures

> I want to make an Analog signal data Acquisition Board. Device consists on 8XADC chips and microcontroller section get data from ADCs on single SPi channel (10MHz), through chip select control (CS). Digital section has 2.4GHz which will creates noise ground bounce.
There are two option in my mind.
1. Make two small PCBs, one Digital section, and second analog section and stack them through header to make size small and ground isolation.




2. Second option is to make a single large PCB contains WIFI controller and analog IC.



 Question: Please suggest which approach is good ,
Suggest some video or link, because PCB has Wi-Fi 2.4GHz, it creates noise on small PCB, small how make isolation between analog and digital section. Thanks


Reference link:
https://e2e.ti.com/support/data-converters-group/data-converters/f/data-converters-forum/646307/ads1255-designing-a-stacked-pcb-connecting-analog-and-digital-ground

Robert Feranec , 03-19-2025, 09:38 AM

It may depend on what your goal is. For example, if they are two separate boards, you can have different variants of these boards with different chips. If it is for one very specific application than you may want to integrate everything on one board. If your main concern is noise, I can't help much as I don't have experience in designing precise analogue - digital mixxed boards. But I would probably do it on separate boards as it is more modular for future.

Atta Rehman , 03-19-2025, 09:50 AM

Thanks Robert ,
I have found one problem in past experience , that increasing number of ADC chips on single board increase board size. and on digital side single board has 2.4GHz , frequency as well . (increased board size and 2.4GHz ) creates noise Ground bounce (resonances).
thats why modular stack suggestion came in mind . (to make small modular boards ).
Question is : Is header stack approach is feasible for 10Mhz communication ?

QDrives , 03-19-2025, 02:33 PM

You do not mention the sensitivity you want / require.
And with the 2.4GHz WiFi, it does not matter if you stack boards or put it all on a single board, as the WiFi will affect it anyhow.
Ground bounce and resonance are not a concern. Noise injection (cross coupling) may be.
As long as your distance between the WiFi section and analog section is large enough, you **could** be ok.
See also https://www.youtube.com/watch?v=9lEtkysFGGg to see how far the noise from digital signals spread.