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https://designers-guide.org/forum/YaBB.pl Modeling >> Transmission Lines and Other Distributed Devices >> Ansoft Q3D 2D solver result mismatch https://designers-guide.org/forum/YaBB.pl?num=1265084328 Message started by neoflash on Feb 1st, 2010, 8:18pm |
Title: Ansoft Q3D 2D solver result mismatch Post by neoflash on Feb 1st, 2010, 8:18pm I have encountered an issue of using Ansoft Q3D's 2D solver. The problem is that I have one demo FR4 trace's geometric information and w-element model extracted by vendor. I was redoing the modeling in Q3D. I can have exactly same sdd21 result. However, the time domain result is very different and I'm sure my own result is incorrect. If I export hspice w element table model, the result is very different. If I use touchstone model, the result is very close. I have no idea what is wrong with the exported w model? Any suggestion? |
Title: Re: Ansoft Q3D 2D solver result mismatch Post by pancho_hideboo on Feb 2nd, 2010, 1:51am Please describe correctly so that eveyone can understand. neoflash wrote on Feb 1st, 2010, 8:18pm:
What do you compare with ? neoflash wrote on Feb 1st, 2010, 8:18pm:
neoflash wrote on Feb 1st, 2010, 8:18pm:
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Title: Re: Ansoft Q3D 2D solver result mismatch Post by neoflash on Feb 2nd, 2010, 6:26am Time domain result means pulse response and PRBS output response of the transmission line. If I use touchstone output model, the prbs response is fairly close. If I use W element, the prbs response is very different and has much less loss. |
Title: Re: Ansoft Q3D 2D solver result mismatch Post by pancho_hideboo on Feb 2nd, 2010, 6:37am neoflash wrote on Feb 2nd, 2010, 6:26am:
Is there any reference ? neoflash wrote on Feb 2nd, 2010, 6:26am:
Is there any reference ? Again describe correctly. I guess followings. - You have some reference as correct results. - Results of transient analysis using s4p(4 ports s-parameters) from Q3D are cosistent with reference results. - But results of transient analysis using W-element from Q3D are not consistent with reference results. My guesses are correct ? If so, Q3D itself is correct. Your settings for dumping W-element model file from Q3D are wrong. Upload your netlist of HSPICE, s4p file and model-file for W-element. |
Title: Re: Ansoft Q3D 2D solver result mismatch Post by neoflash on Feb 2nd, 2010, 9:54am pancho_hideboo wrote on Feb 2nd, 2010, 6:37am:
Your guess is correct. I agree that Q3D is generating consistent result with the reference. However, the dumped w model has problem. I'm also looking into the model file dumped. One problem I see is that the C matrix doesn't change much with increased frequency. If I replace the C matrix with the one in the reference design, the transient result is much closer to the reference. |
Title: Re: Ansoft Q3D 2D solver result mismatch Post by neoflash on Feb 2nd, 2010, 9:56am Actually, I almost see no setting for the w-element export operation. I just right click the analyze menu, and chose "export circuit". Then in the output file selection chose hspice w element format. And click export. Am I missing any option setting? Thanks for your inputs. |
Title: Re: Ansoft Q3D 2D solver result mismatch Post by neoflash on Feb 2nd, 2010, 5:17pm Exported W element based on table data. |
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