Kenny, The standard coupon measurement is performed on a predefined topology = located out of the actual board boundaries. The standard test equipment = measures the reflected TDR wave and provides the average impedance. It = normally checks if the value is within the accepted tolerance range and = main result is 'pass/fail'. Yet, TDR measurement can be taken on an actual trace within the PCB = board boundaries (recommended). You will be required to define a new = 'pass/fail' criteria, unless you keep the same topology defined by the = standard coupon test procedure. If the net is routed as a T-topology, then additional analysis should = be done to separate the effect of each stub on the combined reflection = back at the TDR tip. Note that if the stubs have about the similar = length it will be very difficult to make the separation. =20 - Dori Itzhaki Intel -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] = On Behalf Of Kenny Frohlich Sent: Thursday, August 24, 2006 8:00 AM To: geethukarrthik@xxxxxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: PCB impedance coupon measurement Hi all, Since we're on the subject of PCB impedance coupon measurement, I have = a question on TDR test. I understand that TDR test is performed at the = impedance coupon on the PCB. Can a TDR measurement be taken on an = actual trace on the PCB? If a net is routed as a T-topology, can a TDR = measurement take on this net? =20 Thanks, Kenny Geetha Balasubramanian <geethukarrthik@xxxxxxxxx> wrote: Dear Members, Generally what is the frequency range for PCB impedance coupon = measurement? Is it possible to measue the impedance of the coupon at a = specific discrete frequency? For better accuracy is it necessary to have 2 seperate bands one for USB = full speed (12 Mbps) design and another for USB high speed (480 Mbps) = design? Thanking you all in anticipation Geetha --------------------------------- Talk is cheap. Use Yahoo! Messenger to make PC-to-Phone calls. Great = rates starting at 1=A2/min. ------------------------------------------------------------------ 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 =09 --------------------------------- Want to be your own boss? Learn how on Yahoo! Small Business.=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: =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