Hi Ray, I have used this tool extensively and it does perform quite well. However, there is some error in the W element that it exports. I sent the errors to the "Clinic" and they addressed them, but when you generate a W element you will still need to tweak the Ro value and the Rs value a bit. The Ro value is off on the last 3 decimal places from what the solver gives you. The Rs value is off a bit more. You can use the formulas in the help file to calculate the values. I think that 1% error isn't bad for a piece of software that never read Grover :>). Actually, I haven't really used to the tool for round conductors, but have had good success with the "rectangles". I did speak with Robert Techentin at the clinic when I reported some errors that I found. He gave me some pointers on the software which included using the sweep function to generate values for the C-seg and D-seg. This helps to dial in the asymmetry in the C and L matrices. Sometimes one value must be different than the other in order to obtain the lowest asymmetry in the matix. Perhaps you have a small error in the asymmetry and this is what is contributing to your 1% error. Depending on the application 1% may not really mean too much. Another thing was that sometimes you can reduce the asymmetry by lowering the values of C and D seg as opposed to raising them. I also did what you have done comparing the results from TNT to other methods using "rectangles". I used Linpar, Agilent, Ansoft, and AWR's tool. I found that the results were about the same as what you have obtained using your tools. I took the results one step further and ran a frequency sweep up to about 4GHz on all the values I exported. I was within a couple of tenths of a dB on the insertion loss and return loss with values similar to those you show below. In most cases I believe this to be an acceptable error. Craig -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Raymond Anderson Sent: Wednesday, November 10, 2004 3:25 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Question on 2D field solver 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 ------------------------------------------------------------------ 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