Ray, 2D field solvers usually leave out the internal inductance and inductance formulas include them. Could this be the difference? Does MMTL produce a frequency dependent inductance? Best Regards, On Wed, 2004-11-10 at 23:24, Raymond Anderson wrote: > Here's a question for the field solver guru's on the list: > > I'm currently taking a critical look at the Mayo MMTL BEM 2D field > solver (TNT 1.2.2) that the developers at Mayo have so graciously made > freely available under the GNU GPL to the world. See the si-list > message announcing it for download links: > (//www.freelists.org/archives/si-list/07-2004/msg00311.html) > > In preparation for doing a series of simulations on some via geometries > in packages I decided to validate the accuracy of the MMTL program on > some simple geometries that independent high accuracy answers were known > for. > > I first tried the zero thickness stripline benchmark suggested by Dr. > Rautio at Sonnet Software. > (http://www.sonnetusa.com/products/benchmarking/eval_ch3.asp). The > results were about -0.4% low at 49.8002 ohms. This compares > comparably with a selection of other solvers I've had access to (but on > the low end of the range). > > Mayo MTTL 49.8002 > Polar CITS25 49.96 > Agilent Appcad 3.0.2 49.8 > AWR TXLINE 50.0346 > LINPAR 2.0 50.03 > LINPAR 1.0 50.027 > > Next I selected the case of a pair of parallel round elements as a test > case. The analytical solution for the inductance of this geometry is > given by Grover in chapter 5 of "Inductance Calculations". His formula > is an analytic solution based on first principles. > > Using a test case of conductors 150 microns in diameter on a 500 > micron pitch, Grover's equations yields a loop inductance of > 758.84797 nH for 1 meter long conductors. The same problem modeled in > the MMTL field solver gives an answer of 749.4645 nH. I'm trying to > understand why the field solver answer is about 1.2% low. Is this > reasonable for a 2D MOM BEM solver using quasi-TEM assumptions? I've > tried modeling it several ways (as a pair of parallel circular > conductors far from ground and as a single circular conductor with it's > image reflected across a ground plane) and am getting the same answer > out to at least 2 decimal places. I've also tried upping the density of > the meshing with little real improvement. > > Comments, suggestions and ideas solicited. Thanks! > > -Ray Anderson > > Senior Signal Integrity Staff Engineer > Advanced Packaging R&D > Xilinx Inc. > > > > ------------------------------------------------------------------ > 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 > -- Raj Raghuram Berkeley Design Automation (http://www.berkeley-da.com) 2902 Stender Way Santa Clara, CA-95054-3213 Tel: 408.496.6600 x203 Cel: 408.390.7614 Fax: 408.496.6633 email: raj.raghuram@xxxxxxxxxxxxxxx ------------------------------------------------------------------ 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