{"id":1534,"date":"2014-11-06T10:53:48","date_gmt":"2014-11-06T17:53:48","guid":{"rendered":"https:\/\/blogs.mentor.com\/hyperblog\/?p=1534"},"modified":"2026-03-27T09:22:49","modified_gmt":"2026-03-27T13:22:49","slug":"do-sweat-the-small-stuff","status":"publish","type":"post","link":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/2014\/11\/06\/do-sweat-the-small-stuff\/","title":{"rendered":"DO sweat the small stuff"},"content":{"rendered":"<p>My grandma always told me not to sweat the small stuff, and since she just celebrated her 100th birthday, I am inclined to take her advice.\u00a0 Unfortunately, that advice does not extend well to 10GHz serial links on a PCB, where you really DO need to sweat the small stuff.\u00a0 With edge rates on the order of 50ps (that&#8217;s about 300 mils long on a PCB), 10GHz signals get affected by almost any discontinuity on a board, even those less than 100 mils.\u00a0 So, special care must be taken to ensure that the entire differential path is free from discontinuities.<\/p>\n<p>The biggest discontinuity faced by a 10GHz signal is a via.\u00a0 That means your differential via pair must be designed to as close to 100ohms as possible.\u00a0 This can be achieved by using smaller barrels, removing non-functional pads, and spacing the vias an appropriate distance apart.\u00a0 The best way to design and simulate a differential via pair is by using a <a href=\"http:\/\/www.mentor.com\/pcb\/nimbic\/\" target=\"_blank\" rel=\"noopener noreferrer\">full-wave 3D electromagnetic simulator<\/a>, like the one integrated into the LineSim GHz via modeler.\u00a0 Minimizing or\u00a0preferably eliminating via stubs is also an essential part of the design.\u00a0 This means selecting the right routing layers, or employing the use of backdrilling, or even using blind and\/or buried vias.<\/p>\n<p>I discuss this and other topics related to the successful implementation of 10GHz serial links in my article &#8220;<a href=\"http:\/\/www.pcdandf.com\/pcdesign\/index.php\/current-issue\/241-designer-s-notebook\/9551-designers-notebook-1409\" target=\"_blank\" rel=\"noopener noreferrer\">Ten Steps to Ten GigHertz<\/a>&#8220;.\u00a0 Take a look if you are interested in learning more.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>My grandma always told me not to sweat the small stuff, and since she just celebrated her 100th birthday, I&#8230;<\/p>\n","protected":false},"author":71672,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spanish_translation":"","french_translation":"","german_translation":"","italian_translation":"","polish_translation":"","japanese_translation":"","chinese_translation":"","footnotes":""},"categories":[13],"tags":[],"industry":[],"product":[],"coauthors":[],"class_list":["post-1534","post","type-post","status-publish","format-standard","hentry","category-news"],"_links":{"self":[{"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/posts\/1534","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/users\/71672"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/comments?post=1534"}],"version-history":[{"count":1,"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/posts\/1534\/revisions"}],"predecessor-version":[{"id":10442,"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/posts\/1534\/revisions\/10442"}],"wp:attachment":[{"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/media?parent=1534"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/categories?post=1534"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/tags?post=1534"},{"taxonomy":"industry","embeddable":true,"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/industry?post=1534"},{"taxonomy":"product","embeddable":true,"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/product?post=1534"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/coauthors?post=1534"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}