Broadside coupled diff pairs tend to be less susceptible to vertical registration issues than one would initially think. Best Regards Charles Grasso Senior Compliance Engineer Echostar Communications Corp. Tel: 303-706-5467 Fax: 303-799-6222 Cell: 303-204-2974 Pager/Short Message: 3032042974@xxxxxxxx Email: charles.grasso@xxxxxxxxxxxx; Email Alternate: chasgrasso@xxxxxxxx -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Dunbar, Tony Sent: Thursday, May 05, 2005 10:24 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Broadside coupled line vertical registration In the past, if memory serves me right, Scott McMorrow has contributed valuable information on this topic and it should be locatable in the archives, along with other folk's inputs on the thread. Scott may also have a paper on this, but I'm less sure of that. Regards, Tony -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Bill Wurst Sent: Thursday, May 05, 2005 10:07 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Broadside coupled line vertical registration Mark, While you are evaluating the effects of copper registration, don't forget to also include the effect of manufacturing variations in the thickness of the three dielectrics: top plane-to-trace, trace-to-trace, and bottom plane-to-trace. Each one will have an impact, the degree of which is dependent upon the relative spacing and the amount of variation relative to the nominal thickness, as well as the width of the traces. Regards, -Bill /************************************ / billw@xxxxxxxxxxx / / / / Advanced Electronic Concepts, LLC / / www.aec-lab.com / ************************************ =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Ed Sayre III wrote: > Mark, > Try using a free ware field solver for this. It is a simple=20 > experiment and you will surprised by the results. > We have done some substantial investigations into this and found=20 > that the broadside registration is not as sensitive to variations > as=20 edge coupled spacing and dielectric thicknesses. Of course the > issue=20 is the level of coupling for the lines. The tighter the > mutual=20 coupling the more critical the registration. Thus try your > stack and see. >=20 > Regards > -Ed >=20 >=20 >=20 >=20 > At 02:37 PM 5/5/2005 +0100, Mark Burford wrote: >=20 >>I have an interesting query, I would like to know what you guru's=20 >>think about the effect of the vertical alignment of a broadside=20 >>coupled trace and the error it could potentially introduce to 2D field >>solvers and the traditional transmission line approximation >>formulas=20 for calculating Z0, C and L. To clarify: a perfect >>alignment I am=20 classing as both lines exactly stacked one above the >>other with with=20 core material in the centre an no over hang, worst >>case would be one=20 line being offset to the left or right by 50 >>percent. >> >>Could the potential error introduced be described to a first order >>by=20 decreasing the capacitance by at worst case 0.5? What would be >>the=20 2nd order effects? >> >>Your thoughts I am sure will be as diverse as they are interesting. >> >>Thanks guys >> >>Mark Burford=3D20 >>EngD Research Engineer >> >>------------------------------------------------------------------ ------------------------------------------------------------------ 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: =20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =20 ------------------------------------------------------------------ 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu