Hi,
I have a trace 30um wide, with a thickness of 10um. It is a stripline with
dielectric thickness of 18um above and below the trace. The dielectric
coefficient is 4.5. Running these numbers through a tool on-line for impedance
calculations gives me slightly different numbers for L & C than ANSYS Q2D, but
totally different "L" number than ANSYS Q3D! Here is a summary of my data:
Online Calculator: L=1.888nH/cm, C=2.648pF/cm, and Zo&.704Ohm
ANSYS Q2D (@ 1GHz): : L=2.311nH/cm, C=2.508pF/cm, and Zo0.43Ohm
ANSYS Q2D (@ 1GHz): : L.112nH/cm, C=2.346pF/cm, and Zo=??
My questions:
1. Why "L" is much higher in Q3D compared to Q2D and the calculator? Is this
different inductance than what is reported by the latter two (e.g., loop
inductance vs. self inductance!)?
2. Can Zo in Q3D be calculated directly from these reported numbers by
applying the equation "SQRT(L/C)" or do I need to do some processing to "L"
first? Applying the equation to the #'s obtained above will give
SQRT(11.112nH/2.346pF)h.82Ohm, which is not realistic for my stackup (too high)!
Thanks,
-Adnan
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