At risk of being stoned...the "differential impedance" has very little to do with anything. The key issues is the impedance of the individual lines to their reference. The number "differential impedance" comes from 2 X Z0 which is the characteristic impedance of each of the individual lines. If these lines are balanced mirror images, the current through each of the two Z0 50 ohm resistors cancels and there is no net current out the reference...hence you can use a single 100ohm resistor rather than two 50 ohm resistors. The out fall of this is that everyone thinks differential imp[edance is some magical thing. In my experience it is not. He has touched the holy thing...let us now begin the stoning. TFox At 07:59 AM 6/28/2007, George Korony wrote: >Content-Type: multipart/alternative; > boundary="----=_NextPart_002_0008_01C7B973.5B78CED0" > >------=_NextPart_002_0008_01C7B973.5B78CED0 >Content-Type: text/plain; > charset="iso-8859-1" >Content-Transfer-Encoding: 7bit > >BlankHi All, >I am not a board designer, but I do design parts that other people put on >boards. We are working on a new (patent protected) concept: the " >DC-blocking transmission-line". >Basically the idea is to build a pair of capacitors that can be intercalated >on the differential signal traces, having a controlled characteristic >impedance between the two capacitors, the obvious scope is to reduce the >reflections that may show up due the DC-blocking capacitors. >One request, we have, is that the characteristic impedance between the two >capacitors (treated as a simple transmission line) should be 100 Ohm. >Of course things are not so simple; and my question is: does anyone have a >different approach to this problem? >Thanks for any suggestion, George. > > > > > >------=_NextPart_002_0008_01C7B973.5B78CED0 >Content-Type: text/html; > charset="iso-8859-1" >Content-Transfer-Encoding: quoted-printable > ><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> >Hi All, >I am not a board designer, but I = do design=20 parts that other people >put on boards. We are working on = a new =20 (patent protected) concept: >the " DC-blocking = transmission-line". >Basically the idea is to build a = pair of=20 capacitors that can be >intercalated on the differential signal = traces,=20 having a controlled >characteristic impedance between the two capacitors, = the=20 obvious >scope is to reduce the reflections that may show up due the = DC-blocking >capacitors. >One request, we have, is that the=20 characteristic impedance between the >two capacitors (treated as a simple = transmission line) should be 100 Ohm. >Of course things are not so = simple; and my=20 question is: does anyone >have a different approach to this = problem? >Thanks for any suggestion,=20 George. > > > > >------=_NextPart_002_0008_01C7B973.5B78CED0-- > > >-- Binary/unsupported file stripped by Ecartis -- >-- Type: image/gif >-- File: Blank Bkgrd.gif > > > >-- Binary/unsupported file stripped by Ecartis -- >-- Type: text/x-vcard >-- File: George Korony.vcf > > >------------------------------------------------------------------ >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 >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 technical documents are available at: http://www.si-list.net 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