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 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ::DISCLAIMER:: ---------------------------------------------------------------------------------------------------------------------------------------------------- The contents of this e-mail and any attachment(s) are confidential and intended for the named recipient(s) only. E-mail transmission is not guaranteed to be secure or error-free as information could be intercepted, corrupted, lost, destroyed, arrive late or incomplete, or may contain viruses in transmission. The e mail and its contents (with or without referred errors) shall therefore not attach any liability on the originator or HCL or its affiliates. Views or opinions, if any, presented in this email are solely those of the author and may not necessarily reflect the views or opinions of HCL or its affiliates. Any form of reproduction, dissemination, copying, disclosure, modification, distribution and / or publication of this message without the prior written consent of authorized representative of HCL is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. Before opening any email and/or attachments, please check them for viruses and other defects. ---------------------------------------------------------------------------------------------------------------------------------------------------- ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu