Calculator Tools ("via size") - "Reactance" != Impedance?

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I would like to calculate the impedance of a via. “Calculator Tools” doesn’t seem to have that in the high-speed/transmission-lines section, however there is a “Via Size” that is in the power-current-isolation section and it includes a calculated “Reactance” field. Calculator Tools | 8.0 | English | Documentation | KiCad shows:

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If I calculate Sqrt[1.20723nH / 0.599508pF] I get 44.9 ohms. But the calculator shows “Reactance 3.8 ohms”

  • is this a bug in the calculator that I should report?
  • or do I misunderstand “reactance”, and it is something other than the via’s characteristic impedance?
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I don’t see how you can describe the transmission line impedance of a via without defining all ground structures near it.

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So the documentation needs to be updated as that is a v7 screenshot (v8 got a more tree-type interface)

The reactance calculation follows: pi* inductance / pulseRiseTime, which makes sense

the equation you dropped sqrt(L/C) is the characteristic impedance equation. I guess the question that needs to be asked is… what do you need.

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