Bill, Consider presenting both diff pairs AND cross talk together. For diff pairs, route them parallel for as much length as possible. For cross talk, reduce the parallel length as much as possible. To some PCB Designers, this may seem to be a contradiction (can't the engineer make up his mind?). In reality, there's a method to the madness (electrons are like that you know). Explaining them both at the same time may benefit all in attendance. Thank you, Kevin L. Seaman OrCAD CIS Library Liaison Allegro PCB Library Liaison Sr. Staff PCB Layout Engineer Broadcom Corp. Irvine, CA (949)926-5656 (ext. 65656) -----Original Message----- From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Brooks,Bill Sent: Tuesday, January 31, 2006 7:53 AM To: [log in to unmask] Subject: Re: [DC] Impedance/ Diff pairs/ layer stack up calculator? Thanks George... that was informative. I'd like to get Polar to come do a presentation on diff pairs some time... I think it would make a good DC chapter meeting. Good input from all... I have been buried lately and have not had time to respond... thanks again. Best regards, Bill Brooks - KG6VVP PCB Design Engineer, C.I.D.+, C.I.I. Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510 Datron World Communications, Inc. _______________________________________ San Diego Chapter of the IPC Designers Council Communications Officer, Web Manager http://dcchapters.ipc.org/SanDiego/ http://pcbwizards.com -----Original Message----- From: George Patrick [mailto:[log in to unmask]] Sent: Monday, January 30, 2006 1:21 PM To: [log in to unmask] Subject: Re: [DC] Impedance/ Diff pairs/ layer stack up calculator? An interesting PDF of a presentation given by PJ Kleffner of Polar at one of our meetings last summer is at http://dcchapters.ipc.org/pnw/presentations/20050713_polar.pdf. I thought the displays and some of the things you could do with them were very well done. Unfortunately, our preferred vendors use Apsim, so we are supposed to use it, too. It is a real bear to use and so it usually doesn't GET used and we pester the vendor AE to give us the preferred stacks :) -- George Patrick Tektronix, Inc. Central Engineering, Engineering Design Services P.O. Box 500, M/S 39-512 Beaverton, OR 97077-0001 * 503-627-5272 (voice) * 503-627-5587 (fax) http://www.tektronix.com http://www.pcb-designer.com "Off-Grid and Proud of it!" -----Original Message----- From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Andy Kowalewski Sent: Monday, January 30, 2006 12:58 To: [log in to unmask] Subject: Re: [DC] Impedance/ Diff pairs/ layer stack up calculator? It's certainly the tool of choice. Their stackup builder, combined with their impedance calculator, is the easiest tool of all time to use, especially when you set up all the prepreg, core and foil libraries from different laminators. Building the stackup is super easy with point and click selection. You get a superb visual display as you're building it and for documentation when you're done, and the calculator is as accurate as it's possible to be. Sure it's expensive, but they have a web based rental plan. Check out these web demos: Stackup builder www.polarinstruments.com/help/sb200v6/lang/en/tutorial/stackup_wizard.ht m Impedance control stackup builder: www.polarinstruments.com/help/sb200v6/lang/en/tutorial/addingstructure.h tm Andy Kowalewski +61 (0)2 9499 4853 -----Original Message----- From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Denis Lefebvre Sent: Tuesday, January 31, 2006 1:59 AM To: [log in to unmask] Subject: Re: [DC] Impedance/ Diff pairs/ layer stack up calculator? Bill; We've been looking at the Polar Instruments Si8000. My understanding is that theirs is the "de-facto" standard in impedance calculations and stack-up generation. This is definitely the "high-end" tool. Our interest has been prompted by the variety of results we have seen from various 'free' calculators vs the results we get back from our fabricators. We really want to develop a geometry, by design, that our fabricators will agree with. Denis Lefebvre, CID+ Sr. PCB Designer Finisar Corp (408) 542-3832 -----Original Message----- From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Brooks,Bill Sent: Friday, January 27, 2006 3:25 PM To: [log in to unmask] Subject: [DC] Impedance/ Diff pairs/ layer stack up calculator? We want to evaluate the usefulness of a software tool for calculating differential pairs, and estimating stack up requirements for multi layer boards... Primarily to estimate the correct line width and spacing required in any given design stack up or material combination. Can any of you recommend a tool to do this sort of job that you find useful? I'd like to look at low, med and high end tools and characterize them based on price vs. performance and/or capabilities. Best regards, Bill Brooks - KG6VVP PCB Design Engineer, C.I.D.+, C.I.I. 3030 Enterprise Court, Vista, CA 92083 http://www.dtwc.com <http://www.dtwc.com> Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510 e-mail:[log in to unmask] _______________________________________ Member of the San Diego Chapter of the IPC Designers Council Communications Officer, Web Manager http://dcchapters.ipc.org/SanDiego/ <http://dcchapters.ipc.org/SanDiego/> http://pcbwizards.com <http://pcbwizards.com> ------------------------------------------------------------------------ --------- DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF DesignerCouncil. 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