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PDN analysis issue with S-Parameter models

Question asked by jorge.alvarez on May 25, 2017

Working with HyperLynx PI, I have found an issue when I tried to make a PDN analysis of my design making use of S-Parameter models for the capacitors.

 

To reduce the explanation, I'm going to reduce the circuit to a single capacitor, but actually I facing the problem in an anlysis of the complete PCB's PDN.

 

Then, analyzing a single 470nF ceramic capacitor, I get the right response, no matter whether I work with RLC or S-Parameter model.

You can see it at below picture.

ceramic_470nF_linesim.good.01.JPG

  • Purple. RLC model. Impedance vs. Frequency, without inter-plane capacitance.
  • Red. RLC model. Impedance vs. Frequency, with inter-plane capacitance.

 

The problem comes when I change the RLC model to S-Parameter model.

The behaviour shown at Touchstone viewer is not the right response for the capacitor.

 

Here, is a comparison between RLC and S-Parameter model for the same capacitor.

ceramic_470nF_linesim.wrong.01.JPG

  • Purple. RLC model. Impedance vs. Frequency, without inter-plane capacitance.
  • Red. RLC model. Impedance vs. Frequency, with inter-plane capacitance.
  • Orange. S2P model. Impedance vs. Frequency, without inter-plane capacitance.
  • Yellow. S2P model. Impedance vs. Frequency, with inter-plane capacitance.

 

Is the root cause in the S2P model? Or maybe is it needed to include any input to HyperLynx?

 

* The S-Parameter models are obtained from manufacturer's website (http://ksim.kemet.com/Default.aspx), and before work with them, I have checked the right behaviour of them.

 

Any help will be welcomed in order to understand the problem, and of course, find a solution.

 

BR!

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