Chris, Your right, adding RJ to an eye diagram running in HSPICE (or another more Berkeley Spice type of simulator for that matter) does not add any analysis capability due to the definition of RJ. Actually, the approach can be misleading and does not lend to a complete methodology. A bathtub curve generated by a BERT scan is still an extrapolation it relates the TJ to the sample size (or BER) essentially, it is a much better tool when adding the RJ contribution. Here is why: Any guesses at eye closure or width is based on estimation of the impact of convolving RJ and DJ contributions, and since RJ is unbounded, simply running the simulation for a longer period of time will relate to a larger TJ, or smaller eye width. Take a Noisecom UFX7109 generator and sum AWGN into a limiting amp on one input and a NRZ signal running on the other input so the resulting output is high quality (long tails in the Gaussian pdf) RJ for the NRZ data. Now, measure the jitter. The 1-sigma value will settle to a number for a small number of samples, but the peak-peak jitter will continue to increase with the sample rate. pm me for this data. I used this to dispel the specification myth of peak-peak jitter from the clock manufacturers a while back. Examining individual trajectories due to ISI is relevant (Ransom Stephens, one of our PhD guys, wrote a good paper on equalization at DesignCon2006 on this), especially when the simulation relates S-parameter characterization of the system. We have developed a package model where we optionally include the DJ of the device (TX), contributing DJ of the package, and S11 and S12. When this package/device complete signal integrity model is included into an interconnect model of the system we have a complete picture of how each pathology in the system contributes to the total peak-peak DJ. We deal with RJ differently, since it is different from the other pathologies. RJ is a random noise-VCO origination versus passive interconnect and limitations of the TX driver. Another ancillary benefit of this method is that XTALK, which tricks many of the jitter extraction methods since it looks like RJ (XTALK is deterministic jitter since it is bounded) but is not, is completely extracted and analyzed. Unfortunately, most of the tools and your eye viewing the eye diagram cannot tell the difference between XTALK and RJ so we intentionally do not analyze the RJ contribution when simulating eye diagrams for that reason also. Alfred P. Neves <*)))))><{ Teraspeed Consulting Group LLC 121 North River Drive Narragansett, RI 02882 Hillsboro Office 735 SE 16th Ave. Hillsboro, OR, 97123 (503) 679 2429 Voice (503) 210 7727 Fax Main office (401) 284-1827 Business (401) 284-1840 Fax http://www.teraspeed.com Teraspeed is the registered service mark of Teraspeed Consulting Group LLC -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Chris Cheng Sent: Wednesday, February 15, 2006 1:34 AM Cc: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: HSPICE - adding jitter to ethernet serial link May be its just me but Rj only makes sense when you are trying to extract a BERT curve which seems to be a MATLAB job. If you have your Tx Rj, channel model and jitter transfer of your CDR, the rest of the work is straight forward. > > > At 10:40 AM 2/7/2006 -0800, Ali Burney wrote: > >> Hi, >> >> >> I am running gigabit Ethernet link simulation using HSPICE and have >> a=20 question on adding jitter to the transmitted data. Is there any >> way to=20 add Gaussian jitter to the transmitted data? I know that >> tools such as >> > > >> Hyperlynx allow you to add transmit jitter. >> >> >> >> Thanks and best regards, >> >> >> >> A Burney >> >> >> >> >> >> ------------------------------------------------------------------ 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