[SI-LIST] Re: options for reducing EMI

  • From: Shankar V <shankar-v@xxxxxxx>
  • To: "sherman.chen@xxxxxxx" <sherman.chen@xxxxxxx>, "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
  • Date: Tue, 2 Sep 2014 06:39:46 +0000

Hi Sherman Chen,

To start with, I am not a guru. But I have some suggestions for you.

First u need to find out the source of radiation by what if analysis. Then the 
coupling path if necessary and then fix it.

1.  The PCIe IC could be radiating. You need to isolate the IC and PCB and find 
out.
2. The PCB Trace loop area could be radiating.
3. Noise could be conducted via power lines and radiating.
4. Common Mode Current and Ground Bounce could be the cause. Coupled to a 
nearby connector and cable. What is your topology? Does it have a connector & 
cable? If 1, 2 & 3 do not help, you might want to remove connectors & cables. 
In essence, u might want to strip your board of all possible coupling paths.

Keep us posted of your progress. Let us see... :-)

Regards,
Shankar V


-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On 
Behalf Of Chen, Sherman
Sent: Tuesday, September 02, 2014 2:14 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] options for reducing EMI

Hi SI Gurus,
We are considering the following options in order to reduce the EMI of one of 
our boards, which is mainly caused by the PCIe Gen3 link:

1.       Reducing TX swing.

2.       Turn on SSC.

3.       Slowing down edge rate.
While we are running test to verify which option will bring us the best result 
& least impact, any comments or suggestions from those who had experiences on 
this matter?

Best Regards,

Sherman Chen
Signal Integrity
EMC Global Hardware Engineering
Tel: +86 21 60951100-3329


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