Also, In addition to the experiment Murad is suggesting you could do the same simulation in frequency domain. Construct an equivalent circuit both lumped and and distributed and do S-parameter simulation. If your simulation frequency band is wide enough you will see that your lumped model will give you a low-pass filter response that is artificial.( Just Plot the insertion loss (dB) vs. frequency) Play with the number of segments or lower the frequency you will see the simulation results converge. This will make it clearer what people mean by "not enough bandwith". Also having the results of both frequency domain and time domain simulations provides good insight on how the same effect reveals itself in two different approaches. Bet Regards, "Muranyi, Arpad" <arpad.muranyi@xxxxxxxxx>@freelists.org on 11/30/2001 03:31:55 PM Please respond to arpad.muranyi@xxxxxxxxx Sent by: si-list-bounce@xxxxxxxxxxxxx To: si-list@xxxxxxxxxxxxx cc: Subject: [SI-LIST] Re: lumped model vs distributed model Jason, I am sure you will get many good theoretical answers to this question. However, I would suggest that in order to get a better understanding, try it out yourself! If you have a spice simulator, build a network with a single RLC lump, and compare it with say 10 of them in series, or 100 of them in series (don't forget to divide the individual element values by the number of lumps, though). This is not too hard if you know how to make a subcircuit... For the "driver" you can just use a Thevenin circuit, with a Pulse (or PWL) source where you can vary the edge rate from very steep (1.0 ps) to less steep (10 ns). Then run the simulations and put the waveforms on top of each other. You should see pretty good differences... Arpad Muranyi Intel Corporation =========================================================== -----Original Message----- From: Jason D Leung [mailto:jleung@xxxxxxxxxxxxxxx] Sent: Friday, November 30, 2001 12:19 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: lumped model vs distributed model Hi everyone: For transmission line we can always use a lumped R,L,C model to represent a simple transmission line, or we can use a distributed model .(I know that the distributed model is more accurate and for high freq application we should use this model) But my question is : what is the main difference between the lumped model and distributed model? If we are just using the lumped model for our SI simulation, what are we going to miss ? looking forward for your insight thanks Regards Jason Leung ------------------------------------------------------------------ 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 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 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 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