Calculation Notes
A microstrip is a type of electrical transmission line consisting of a conducting strip separated from a ground plane by a dielectric layer called the substrate. The embedded microstrip also has a dielectric above it, such as a soldermask.
Factors that influence the impedance calculation include:-
- Trace thickness (t)
- Substrate height (h)
- Trace height above plane (hp)
- Trace width (w)
- Substrate dielectric (εr)
Z_{o}\approx \frac{60}{\sqrt{\varepsilon_{rp}}}\times\ln\left(\frac{5.98h_{p}}{(0.8w+t)}\right)
\varepsilon_{rp}\approx \varepsilon_{r}\bigg[1-exp\Big(-1.55\frac{h}{h_{p}}\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
Disclaimer: The information and this tool are provided with no liability of any kind whatsoever, use at your own risk.