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National Instruments Graphical User Interface Ultiboard User Manual

Page 197

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Chapter 6

PCB Calculators

NI Ultiboard User Manual

6-14

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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)))