Calculation Notes
A differential symmetric stripline is constructed of two traces placed equidistantly between two plane layers, separated by a dieletric.
Factors that influence the impedance calculation include:-
- Trace thickness (t)
- Substrate height (h)
- Trace width (w)
- Trace spacing (s)
- Substrate dielectric (εr)
Z_{o}\approx \frac{60}{\sqrt{\varepsilon_{r}}}\times\ln\left(\frac{1.9\times(2h+t)}{(0.8w+t)}\right)
Z_{d}\approx 2\times Z_{o}\times\bigg[1-0.347\,exp\Big(-2.9\frac{s}{2h+t}\Big)\bigg]
References:
- RF Design Guide Systems, Circuits and Equations (ISBN 0-89006-754-6)
- High-Speed Digital Design (ISBN 0-13-395724-1)
- Signal Integrity Issues and Printed Circuit Board Design (ISBN 0-13-335947-6)
- IPC-2141 Controlled Impedance Circuit Boards and High Speed Logic Design
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