Thanks for your answer first of all !Don't think it's an EM problem in the first place. Exact frequency characteristic is primarily set by dielectric losses and to some amount by conductor (resistance, skin effect, inductance). For the frequency range of interest (< 10 MHz) it can be well described by lumped model parameters.
Thanks for your suggestion !I fully agree to FvM: separate the problem into (a) EM analysis of the PCB routing and (b) lumped circuit model of the capcitors.
If you are interested in <10 MHz only, the routing can be considered a lumped element itself (series L + R and possibly some small shunt C), so it can analyzed at a few frequencies to extract the equivalent circuit model. The free Sonnet Lite software would be ok for analysis and circuit model extraction, but only the full product offers PCB data import. Keysight ADS would also be a very capable EM solver which offers all required functionality.
Both tools are based on MoM, method of moments. You asked about FEM - that would be overkill for this simple task, and only introduces user error if you are not experienced with the tool. The MoM tools are more user friendly and require less training to get reliable data.
I'm not sure what you mean here. If you mean extra capacitance: that would be wideband, shifting resonances but not creating extra resonances.proximity effect between the capacitor
You got it right.. I thought that the extra peaks in ESR and Z curves are caused by inductive effects between close capacitors in the bank at different frequencies, but you are saying that the extra peaks are actually due to something happening in the inside of capacitors themselves. In your opinion, is it possible to predict this behaviour during initial design stage, using simulation tools, before measuring the impedance of the physical component? Or is there a better way than simulation?I'm not sure what you mean here. If you mean extra capacitance: that would be wideband, shifting resonances but not creating extra resonances.
Proximity effect is an inductive effect, and will be captured by the MoM solvers that I mentioned. However from my 25+ years work as an EM specialist: this is not relevant for your case. Skin effect and proximity effect are not causing the extra resonances that you showed.
If you have captured your layout effects already, including capacitive and inductive coupling between the lines, the extra resonances seem to be caused by a more complex behaviour of the discrete components.
I really think you need to measure the discrete components, any EM modelling would be very approximate with a lot of guesses.In your opinion, is it possible to predict this behaviour during initial design stage, using simulation tools, before measuring the impedance of the physical component?
Yes, but @dome_palp mentioned that he did RLC modeling using Ansys Q3D. That tool can model mutual inductance, so I assumed that the layout model is "good enough".Thus I think it can be an effect of bus bar interconnect. Inductive coupling rather than proximity effect.
@FvMYes, but @dome_palp mentioned that he did RLC modeling using Ansys Q3D. That tool can model mutual inductance, so I assumed that the layout model is "good enough".
In solution 1 I used a very simple series RLC circuit, with the R that represents the ESR with values changing with frequency, while L and C were kept constant. All these values come from a measurement of a single film cap.What equivalent circuit did you use for the capaciators in solution 1? Any series inductance included to model the distributed nature of the capacitor plates?
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