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[SOLVED] Regarding EMI shield problem

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ashugtiwari

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Hi All,
In PCB layout designing if non-EMF analog and high frequency digital components (which prone to radiate EMF while operating) are kept under single EMI shield with optional chasis, will the analog section be affected through noise generated by EMI or the shield will suppress it. Please tell me some more techniques for EMI suppresion and shielding.

Thanks in Advance,
Ashutosh
 

AFAIK/ISTR If the analogue section is inside the shield then it is liable to be prone to interference from the radiating sections also inside it. You would be better dividing it with a split shield (like a partition/wall in the shield).
 
Thanks for reply,
how to use board techniques for minimizing EMI without having shield. How the layout can be optimized. Please reply.

Thanks once again,
Ashutosh
 

keeps inputs away from noisy tracks, put grounds between them, use ferrite beads etc...

Try looking for articles on EMC prevention, get some books on the subject.
 
Route the Signals with respect to reference plane and mostly in Strip line Environment.Better route the analog and High speed digitals in different layers and orthoganal to each other to have reduced EMI

Regards
Rajan K
 
You can sprinkle ground vias to the copper area also you can do via stitching around the critical signals trace hope this will help you ,see attached Pic for more clarity

regards
Antarveena
 

Ashutosh, there are many facrtors to be considered for the EMI issues while designing a board. An EMI shield may not be required at all if the board is designed properly.

1. PCB is 2 layer or 4 layer or more ?
2. What is the frequency of operation for the intentional radiator ?
3. What are the other crystals used on this board ?
4. Have you followed all the guidelines given by the IC manufacturer for proper pcb routing guidlelines ?
5. Have you done any pre-compliance testing to see if your unit is meeting the specs or failing ?
6. What EMI standards do you need compliance for ? FCC Class A or B or EN55022 ?

If you can be more specific, I can probably help.
 

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