Well it all depends on the shape of the filter response. Is it = single-pole RC? 3rd-order Chebyshev? Gaussian? The ratios listed below = are true for Gaussian but not necessarily for all responses. For = instance, for today's more brick-wall-like scope responses, the 10-90 = numerator is closer to 0.42. =20 Art Porter Agilent=20 -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] = On Behalf Of Cortex.Chen@xxxxxxxxxxxx Sent: Thursday, January 05, 2006 7:26 PM To: tom@xxxxxxxxxxxxx; rula.bakleh@xxxxxxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Maximum frequency consideration for high-speed = digital analysis of differential signals 0.35/Tr ---- 10% to 90% 0.22/Tr ---- 20% to 80% =20 Regards, =20 Cortex ________________________________ From: si-list-bounce@xxxxxxxxxxxxx =A5N=B2z Tom Dagostino Sent: 2006/1/6 [=ACP=B4=C1=A4=AD] =A4W=A4=C8 10:03 To: rula.bakleh@xxxxxxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Maximum frequency consideration for high-speed = digital analysis of differential signals I'm not sure how you are computing your bandwidth. If you have a 25 = psec risetime (assuming 10-90%) your -3dB bandwidth is 0.35/25psec or 14 GHz. When analyzing bandwidth requirements for systems like this most people = talk about passing the 3rd or 5th harmonic of the clock. In your case that = is 7.5 or 12.5 GHz. Some analysis of your system requirements is in order. Tom Dagostino Teraspeed(R) Labs 13610 SW Harness Lane Beaverton, OR 97008 503-430-1065 tom@xxxxxxxxxxxxx www.teraspeed.com Teraspeed Consulting Group LLC 121 North River Drive Narragansett, RI 02882 401-284-1827 -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of rula.bakleh@xxxxxxxxxx Sent: Thursday, January 05, 2006 2:19 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Maximum frequency consideration for high-speed digital analysis of differential signals Hi Everyone, I'm designing a differential signal for the Rocket I/O interface. My = signal speed is 5 Gbit/sec, operating frequency is 2.5 GHz, and fastest edge = rate is 25 psec or 40 GHz. In regards to performing channel analysis, what is the highest frequency content to consider when designing this particular differential signal serial link? If I am measuring or simulating S parameters for various portions of this link what is the highest frequency of interest that I = need to consider as a rule of thumb and why? Is it the operating frequency only, multiples/harmonics of the operating freq, edge rate frequency (f=3D1/trise), multiples/harmonics of the edge = rate freq, or some fraction of the edge rate? I'm finding conflicting information: some people say that it's the full edge rate, others say = 0.35 or 0.5 of the edge rate, and yet others say multiples of the edge = frequency should be taken into account for analysis and design. I'm hoping that somebody could shed some light on this topic for me. Thank You, Rula Bakleh ------------------------------------------------------------------ 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: =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: =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