Use a field solver. Steve. On 7/1/2011 1:04 AM, Jayasuryan KG wrote: > Dear Rohit, > > Thanks for the detailed reply. Is there any tool to make sure that the > impedance of the individual trace is 45 Ohm and it is 90 Ohm (no mutual > coupling) when it will be differential? > How can we make sure it is meeting the our requirement in manufacturing too. > Impedance coupons are the only way or do we have any other solution(s)? > > Best Regards, > Jayasuryan > > -----Original Message----- > From: Rohit MISHRA > Sent: Thursday, June 30, 2011 7:06 PM > To: si-list@xxxxxxxxxxxxx > Cc: suryan_tvm@xxxxxxxxxxx > Subject: RE: [SI-LIST] Re: Differential Pair - Impedance Question > > Jayasuryan, > > When you talk about "45 Ohm impedance for individual", you are talking about > characteristic impedance(Z0) of individual or single ended line which is > intrinsic to that line only and can't be changed by changing differential > impedance actually it is other way around, once you have set the > characteristic impedance of your single ended line then differential > impedance between two lines depends on characteristic impedance(Z0) of lines > and mutual coupling between them. > > So if characteristic impedance of single ended line (D+& D-) is Z0 and > coupling coefficient between them is k then > > Zdiff = 2 * Z0 ( 1- k) or > = 2 (Z11 - Z12) > > -> k = 0, Zdiff = 2 * Z0 > > Hope it should be clear now. > > Rgds, > Rohit > > > > -----Original Message----- > From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On > Behalf Of steve weir > Sent: Thursday, June 30, 2011 1:21 PM > To: si-list@xxxxxxxxxxxxx > Subject: [SI-LIST] Re: Differential Pair - Impedance Question > > The single-ended impedance can be half the differential impedance when > the lines have no mutual coupling. > > Steve > On 6/30/2011 12:02 AM, Jayasuryan KG wrote: >> Dear Experts, >> >> >> I have a question regarding differential pair. >> >> In my UBS differential pair, the impedance is 90 Ohm. >> >> >> >> Is it possible to achieve 45 Ohm impedance for individual (D+ and D+) >> traces(45 Ohm+45 Ohm? Ohm) in the differential traces? >> >> >> >> Kindly share your feedbacks. >> >> >> >> Thanks in advance. >> >> >> >> Best Regards, >> >> - Jayasuryan >> >> ------------------------------------------------------------------ >> 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 >> >> >> > -- Steve Weir IPBLOX, LLC 150 N. Center St. #211 Reno, NV 89501 www.ipblox.com (775) 299-4236 Business (866) 675-4630 Toll-free (707) 780-1951 Fax ------------------------------------------------------------------ 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