Paul -- Is it safe to assume in your third paragraph below that you meant "frequency-dependent R's"? Voltage dependent resistance is nonlinear, e.g. diodes. Transmission lines may be nontrivial to model, but fortunately they are strongly linear in the GHz frequencies. Paul Levin wrote: > Dear Goutham, > > Inductance will force the high frequency components of the return > current to be shared equally by the two planes. The decoupling > capacitance in the vicinity of the driver *should* sort out the return > current and bring it to the correct voltage plane. Plane thickness is > not an issue: At these high frequencies, the skin depth is smaller than > any common copper thickness. > > The low frequency components will flow as one would expect from > voltage and load resistance. > > Intermediate frequency components will be somewhere in between. > The transition occurs in the region where the inductive reactance of > the transmission line overtakes the resistance (bulk or skin as appro- > priate) of the transmission line. If you feel up to some fun math, you > could model this as a four-winding transformer (two windings for the > trace and one for each shield) in series with voltage-dependent R's. > > Paul Levin > Senior Principal Engineer > Logic Innovations > _____________________________ > > Goutham.S@xxxxxxxxxx wrote: > > >>Hi, >> >>In a stripline environment, with the signal trace equidistant from a ground >>plane and a power plane, what will the return current path be for a H-L and >>L-H >>transition be? Also what percentage of the return current will flow thro the >>ground and power planes, assuming the return current will be ditributed >>between >>the two ref planes. Also the two ref planes are assumed to have equal >>thickness. >> >>Any answers or comments........ >> >>Regards >>Goutham Sabavat >>Force Computers india Pvt Ltd >> >>------------------------------------------------------------------ >>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 > > > > -- ------------------------------------------- Steven D. Corey, Ph.D. Time Domain Analysis Systems, Inc. "The Interconnect Modeling Company." http://www.tdasystems.com email: steve@xxxxxxxxxxxxxx phone: (503) 246-2272 fax: (503) 246-2282 ------------------------------------------- ------------------------------------------------------------------ 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