Designing controlled-impedance vias
时间：04-06
整理：3721RD
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I'm attempting to make a "coaxial" type via hole as described in an EDN magazine article by Thomas Neu. link: Spreadsheet with calculations and a reference link to the EDN design article
Some of the formulas aren't working as planned and do not seem to make sense.
Has anyone ever encountered this approach?
It's based on two wire inductance and capacitance models that aren't exactly the same as those I can find for twisted pair cables.
I might be experiencing a unit problem as I'm not certain I have this nailed down.
Some of the formulas aren't working as planned and do not seem to make sense.
Has anyone ever encountered this approach?
It's based on two wire inductance and capacitance models that aren't exactly the same as those I can find for twisted pair cables.
I might be experiencing a unit problem as I'm not certain I have this nailed down.
Checking the quantities in your calculation for plausibility would be a first step. I see, that your are putting in absolute(!) permeability of 1, omitting the constant μ0. You also have an expression Z = L/C (with a factor), which misses a square root.
perfect! Permeability was it, I just forgot to do the sqrt() function on my gdocs spreadsheet only.
Thanks.