My quick 2 cents, The effectiveness of guard traces depends on whether you are talking microstrip or stripline. My understanding, based on a conversation with Mr. Bogatin just this past week, and I don't mean to speak for him, is that guard traces are pretty useless on microstrip layers. The fringe fields more or less leap frog the guard trace to the victim. You get about the same result by just extending the spacing as you would have to anyway to implement the guard trace, and you avoid issues with termination and standing waves. However, guard traces on stripline layers can be useful if implemented properly. That's about all I can say. I've never used guard traces in any designs. Brian Moran Signaling Development Group Client Platforms Intel Corporation -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Lambert Simonovich Sent: Thursday, May 24, 2012 5:15 PM To: ken@xxxxxxxxxxxxxxxx; EMC-PSTC@xxxxxxxxxxxxxxxxx; 'SI-LIST' Subject: [SI-LIST] Re: Guard Traces - Use 'Em, or Not? Ken et al, Good blog post. I have been doing a little research myself; hopefully to put the subject to bed. I was putting the finishing touches on a white paper when you posted your link. Abstract: To guard or not to guard? That is the question often asked by digital hardware design engineers. As bit rates continue to climb, there is increased debate on whether to use guard traces to control crosstalk in high-speed digital signaling. By doing so, it is believed the guard trace will act as a shield between the aggressor and victim traces. On the other hand, the argument is that merely separating the victim trace to at least three times the line width from the aggressor is good enough. This paper studies the application of guard traces and quantifies the results against non guarded scenarios. Conclusions: This study has shown that adding a guard trace, at 3 times the line width, terminated at both ends with 50 Ohms, does little to improve crosstalk on the victim. In fact, in most cases, it was worse. The same was true when the guard trace was grounded only at each end. But adding a ground-stitched guard trace, with the same spacing, showed it was the best solution for microstrip, and had little to no benefit for stripline. However, by increasing the spacing to 5 times the line width in microstrip, the crosstalk, for all intensive purposes, was the same. In stripline, there was no benefit in adding a guard trace for digital signaling. You can download a copy from my website. Hope everyone finds it useful. Here is the link: http://bit.ly/KSM5BZ Best regards, Bert Simonovich, Consultant & Founder LAMSIM Enterprises Inc. "Innovative Signal Integrity and Backplane Solutions" Email: lsimonovich_at_lamsimenterprises.com Blog: http://blog.lamsimenterprises.com/ LinkedIN: http://www.linkedin.com/in/bertsimonovich Web Site: http://lamsimenterprises.com/ ======================================================= -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Ken Wyatt Sent: May-24-12 2:43 PM To: EMC-PSTC@xxxxxxxxxxxxxxxxx; SI-LIST Subject: [SI-LIST] Guard Traces - Use 'Em, or Not? Hi Group, After noticing the continued banter and discussions regarding guard traces in both the EMC and SI groups over the past months, I decided to consult a couple experts on the subject - Howard Johnson and Eric Bogatin. I summarized their thoughts in my latest blog posting on the Test & Measurement World web site: http://www.tmworld.com/blog/The_EMC_Blog/41806-Guard_Traces_Use_Em_or_Not_.p hp. I invited both to add any additional comment, if they wished. Feel free to add to the discussion. Cheers, Ken _______________________ Kenneth Wyatt Wyatt Technical Services LLC Woodland Park, CO Email Me! | Web Site | Blog Subscribe to Newsletter Connect with me on LinkedIn ------------------------------------------------------------------ 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 ------------------------------------------------------------------ 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 ------------------------------------------------------------------ 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