Chapter 6
PCB Calculators
©
National Instruments Corporation
6-9
4.
Click
Calculate
. Results of the calculation appear in the
Calculation
Results
area. They also appear in the
Results
tab of the
Spreadsheet
View
.
Note
If you chose
User Defined Zo
in the previous step, the
Per Length Unit
and the
Differential Impedance
are the only values that appear in the
Calculation Results
area
of the
PCB Differential Impedance Calculator
dialog and the
Results
tab when you click
Calculate
.
5.
Click
Close
to close the
PCB Differential Impedance Calculator
.
Microstrip Differential Impedance Equations
The equations used to perform the microstrip differential impedance
calculations are:
Z0 = 87/(sqrt(Er + 1.41)) * ln(5.98*H/(0.8*W+T))
Tpd = 58.35247*sqrt(Er+1.41)
C0 = Tpd/Z0
L0 = C0*Z0*Z0
Zdiff = 2*Z0*(1-0.48*exp(-0.96*S/H))
Embedded Microstrip Calculations
Complete the following steps to perform embedded microstrip differential
impedance calculations:
1.
Select
Tools»PCB Differential Impedance Calculator
.
2.
Select
Embedded Microstrip
in the
Type
drop-down list.
3.
In the
Input Data
area, edit the following fields as desired.
•
Input Length Unit
—Select mils or millimeters.
•
Dielectric Height (H1)
—Refer to the figure below.
