Hi Arpad: I am trying your approach and I am using xfx in XTK to capture the L,C and R lumped values. Assumption : I am using a Trise of 100 ps and Er=3.5 and 1 meter long transmission line to exaggerate the effect *******the configuration for the stackup CONFIG SINGLE e: 1.00 tan:0.035 rho:0.667 DIELECTRIC e: 3.50 HORIZ_PLANE y: 1.2 13.8000 CONDUCTOR 1 RECTANGLE x: 0 5.00000 y: 7.2 7.8000 GROUND HORIZ_PLANE y: 13.8 15 GROUND HORIZ_PLANE y: 0.00000 1.2000 ; and the .tlp file is ************ Configuration Name: SINGLE Conductors: 1 Conductor index: 0 name: $$GND$$ Conductor index: 1 name: 1 i j Lij Cij Ze Zo Se So Fwdx Rvsx from to (nh/in) (pf/in) (ohms) (ohms) (ns/ft)(ns/ft) (s/s) (v/v) -------------------------------------------------------------------------- 1 1 8.748 2.872 55.19 - 1.90 - - - : LOSS MATRICES i j Rsij Gij Rdcij Gdcij from to (ohm-nsec^.5) (mS-ns) (ohms) (mS) PER INCH -------------------------------------------------------------------------- 1 1 0.45405 0.100524 0.22233 0.00000 ; ******** In the spice deck , I have the following for the lumped transmission line model: c1 in 0 56.55p ****c1=2.872*39.37inch /2 rp in rmid 8.753 ***rp=0.22233*39.37 inch l1 rmid out 344.4n ****l1=8.748*39.37 inch c2 out 0 56.55p and for the distributed model I have the following for the spice deck: *********** .subckt DSPKG in out ref c1 in ref 5.655p *whatever the values I have divided by 10 sections rp in rmid 0.8753m l1 rmid out 34.4n c2 out ref 5.655p .ends DSPKG ********************** xdspkg1 in_dist pkgsec1 gnd dspkg xdspkg2 pkgsec1 pkgsec2 gnd dspkg xdspkg3 pkgsec2 pkgsec3 gnd dspkg xdspkg4 pkgsec3 pkgsec4 gnd dspkg xdspkg5 pkgsec4 pkgsec5 gnd dspkg xdspkg6 pkgsec5 pkgsec6 gnd dspkg xdspkg7 pkgsec6 pkgsec7 gnd dspkg xdspkg8 pkgsec7 pkgsec8 gnd dspkg xdspkg9 pkgsec8 pkgsec9 gnd dspkg xdspkg10 pkgsec9 out_dist gnd dspkg * However, when I compare the lumped and distributed model together , I didn't see any difference, do I miss something here or ... thanks Jason Leung "Muranyi, Arpad" wrote: > 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