National Instruments Graphical User Interface Ultiboard User Manual page 197

Chapter 6 PCB Calculators
NI Ultiboard User Manual
Asymmetric Stripline Differential Impedance Equations
The equations used to perform the asymmetric stripline differential
impedance calculations are:
Z0 =
(1-H/(4*H1))*80*ln(4*(2*H+T)/(0.67*3.1415926*(0.8*W+T)))/sqrt(Er)
Tpd = 84.66667*sqrt(Er)
C0 = Tpd/Z0
L0 = C0*Z0*Z0
Zdiff = 2*Z0*(1-0.347*exp(-2.9*S/(H+H1+T)))
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