HFSS/SIwave提取S参数用于SPICE仿真时的一些建议
Setting up HFSS and SIwave for Nexxim TransientAs we learn more about the interactionsbetween HFSS and SIwave on one hand, and Nexxim’s transient solver on theother, we’ve come up with some guidelines for improving the results.
[*]Use Discrete Sweep rather than Fast or Interpolating.
The algorithms used within HFSS and SIwave to do interpolation do not preserve causality.
[*]Use a frequency sweep that gets as close to DC as possible.
You may be planning to excite your structure with a source of limited frequency extent, but if you’re using Nexxim’s transient solver, you’ll need a good DC point, since DC must be solved to give transient a starting point.
Also, since sine waves and other ostensibly band-limited sources must start from zero for times less than zero in Nexxim’s transient, there may be more low-frequency content than you expect.
[*]Remember the signal-integrity rule of thumb, that the knee frequency of a pulse is somewhere around 0.35/risetime to 0.5/risetime of the signal.
(There can be significant energy above that point, depending on the shape of the pulse.) So a 100ps risetime signal requires a top frequency of simulation of at least 5GHz (and often much higher), no matter what the period of the signal is.
[*]Avoid dielectric materials with a constant non-zero loss tangent; they are non-causal.
Use either lossless materials, or “frequency-dependent” ones.
[*]If you’re planning on using convolution, it’s best to use a uniform frequency sweep.
[*]Eliminate any unused ports; extra ports put a burden on the state-space fitter, particularly if you choose to enforce passivity. 感谢阿！！！！！！！ 谢谢了，可惜我不能在这个版评分。
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