Hithesh, You are correct for calculating the total Vswing = 0.46, but I am not sure why you are multiplying by 2 because the load is 50 Ohms. Your 0.46 volt total swing is what the buffer is able to drive into a 50 Ohm load. This depends entirely on the I-V curve of the buffer. From your rather cryptic email it seems that you are surprised that multiplying 0.46 by 2 doesn't give you 1.8. That will only happen if the buffer's I-V curve is also a 50 Ohm straight line. It seems that this buffer has a different I-V curve... I hope this helps, Arpad ================================================================ -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Hithesh Sent: Friday, October 12, 2012 11:54 AM To: SI-List Subject: [SI-LIST] Re: IBIS Ramp data Hi All, Thanks for the reply. I knew he IBIS specs. I did the 80-20% math. The numbers didn't add up. So I posted. The dv/dt example was for 1.8V Medium drive strength, 50 ohm load, taken from SAM9G25 ibis (bpp1v8_md) dv = 0.28, So total V is (0.28/0.6)=0.46. It's 50 ohms load, so x2 = 0.93v ? Where am I going wrong. -Hithesh On Fri, Oct 12, 2012 at 9:45 PM, Tom Dagostino <tom@xxxxxxxxxxxxx> wrote: > Hitesh > > The answer to your question is in the IBIS spec. The dV is voltage > difference between the 20% and 80% values of the peak to peak swing of the > output as loaded in the extraction of the VT waveform. The dT is the time > difference between those two points. For a CMOS like output the falling > ramp is from the falling waveform with a load terminated to Vdd and the > rising is from the rising waveform whose load is terminated to ground. > > Tom Dagostino > > Teraspeed Labs > 9999 SW Wilshire St. > Suite 102 > Portland, OR 97225 > USA > > 971-279-5325 Office > 971-279-5326 FAX > 503-430-1065 Cell > > 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 Hithesh > Sent: Friday, October 12, 2012 8:12 AM > To: SI-List > Subject: [SI-LIST] IBIS Ramp data > > Basic question about ramp data specified in IBIS file - How is the ramp > data > specified? > For example, if the dv/dt for 1.8v is 0.28/0.185n Are the dv and dt number > random? > > Thanks, > -Hithesh > > > ------------------------------------------------------------------ > 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 forum is accessible at: > http://tech.groups.yahoo.com/group/si-list > > 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 > > > ------------------------------------------------------------------ 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 forum is accessible at: http://tech.groups.yahoo.com/group/si-list 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 ------------------------------------------------------------------ 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 forum is accessible at: http://tech.groups.yahoo.com/group/si-list 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