{"id":787,"date":"2012-10-10T15:48:34","date_gmt":"2012-10-10T22:48:34","guid":{"rendered":"https:\/\/blogs.mentor.com\/hyperblog\/?p=787"},"modified":"2026-03-27T09:19:29","modified_gmt":"2026-03-27T13:19:29","slug":"return-current-on-a-stripline","status":"publish","type":"post","link":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/2012\/10\/10\/return-current-on-a-stripline\/","title":{"rendered":"Return current on a stripline"},"content":{"rendered":"

In previous blogs, I have discussed the importance of an uninterrupted, intact reference plane for signals.\u00a0 But, what if you have two reference planes for your signal?\u00a0 This is probably true of most signals in any board over 6 layers – a great deal of routing exists on the inner layers.\u00a0
\nIn a symmetrical stripline, the return current is shared equally between both planes.\u00a0 So, both planes need to be solid.
\nOften, however, a “dual stripline” structure is used to squeeze in as many routing layers as possible into a board stackup.\u00a0 Most dual striplines have a large gap between the two\u00a0signal layers to minimize layer-to-layer crosstalk, which prompts the question: do I need to worry about the further reference plane?\u00a0 In order to answer that question, you need to understand that return current scales linearly with the distance to the planes.\u00a0 So, if I have a dual stripline structure where the signal layers are spaced 4 mils from their nearest reference plane and 12 mils apart, that means I have a 4:16 ratio of distances to reference planes for the signal layers (if I neglect the copper thickness of the signal layers), which reduces to 1:4.\u00a0 That means that 80% of the return current will go into the nearer reference plane and 20% will go into the further one.\u00a0 I discuss this\u00a0(with pictures!)\u00a0in the following article:
\nhttp:\/\/pcdandf.com\/cms\/component\/content\/article\/246-2012-articles\/9315-pcb-design<\/a><\/p>\n

In HyperLynx DRC, you can set a threshold for the required percentage of return current in a plane to include the plane in the check, for DRCs like the Nets Crossing Gaps DRC and Reference Plane Change DRC.\u00a0 It’s a great way to ensure that you don’t have large amounts of current radiating into your EMI chamber!<\/p>\n","protected":false},"excerpt":{"rendered":"

In previous blogs, I have discussed the importance of an uninterrupted, intact reference plane for signals.\u00a0 But, what if you…<\/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":[1049,1051,1052,1107,1131],"industry":[],"product":[],"coauthors":[],"class_list":["post-787","post","type-post","status-publish","format-standard","hentry","category-news","tag-drc","tag-emc","tag-emi","tag-return-current","tag-stripline"],"_links":{"self":[{"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/posts\/787","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=787"}],"version-history":[{"count":1,"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/posts\/787\/revisions"}],"predecessor-version":[{"id":10345,"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/posts\/787\/revisions\/10345"}],"wp:attachment":[{"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/media?parent=787"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/categories?post=787"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/tags?post=787"},{"taxonomy":"industry","embeddable":true,"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/industry?post=787"},{"taxonomy":"product","embeddable":true,"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/product?post=787"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/wp-json\/wp\/v2\/coauthors?post=787"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}