Hi Brian, 1) What is your single ended line trace width?, assume it is 5 mils for now. 2) What is your Diff line width and spacing?, assume it is 4x4 for now. (4 mil width and 4mil spacing to achieve 90/100 ohms) With the above numbers the SDA line is spaced 5x apart from the SERDES considering the 4mil spacing in the DIFF pair, if you consider the single ended line width for spacing analysis you are 4x away from the DIFF SERDES. I don't think we can do spacing more than 4x/5x practically in any boards. So you should be good to go. Most of the SERDES lanes the design requirement is only 3x from other high speed signals with steep rise time to minimize crosstalk. Thanks & Regards Lakshminarayanan. S -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Massoud Shakeri Sent: Tuesday, August 09, 2011 11:38 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: crosstalk Brian, If the length of these two tracks is 1 or 2 inches at 20mils distance, usually it should not be a problem, because SDA is around 1 Mbps and orders of magnitude less than SERDES. But there are some issues that you need to consider: - Say you have 300 mV budget for crosstalk on SERDES, and crosstalks from other lines are already close to the budget, so passing SDA line close to SERDES may cause crosstalk to surpass the budget, and you need to change something to bring it lower. - Crosstalk from SERDES on SDA usually cannot make SDA to malfunction. But more important issue is SDA line can be a good antenna for 10GB/s signal if it's on top or bottom layer, and you may have more trouble with EMI/EMC. - For an exact answer you need to do a post-routing simulation, for example with Hyperlynx. It does not take much time to do that. You can perform simulation on a few nets including SERDES and status lines close to them. Massoud Shakeri -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of tianluchuan2005 Sent: Monday, August 08, 2011 6:12 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] crosstalk I have a question need your help. There is a via, the net is SDA of I2C, is close to 10Gb/s SERDES, the distance is about only 20mils. And I am afraid if there is the crosstalk between the SDA and SERDES. I don't know if the distance is safe, or the SDA have no influence to SERDES ? Thanks ! -Brian Tian ------------------------------------------------------------------ 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 technical documents are available at: http://www.si-list.net 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. It shall not attach any liability on the originator or HCL or its affiliates. Any views or opinions presented in this email are solely those of the author and may not necessarily reflect the 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 the author of this e-mail is strictly prohibited. If you have received this email in error please delete it and notify the sender immediately. Before opening any mail and attachments please check them for viruses and defect. ----------------------------------------------------------------------------------------------------------------------- ------------------------------------------------------------------ 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 technical documents are available at: http://www.si-list.net 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