Symmetric Stripline Impedance Calculator


PCB stripline refers to a type of trace/transmission line that is routed in the inner layers of the PCB. Due to this, it is enclosed by a single material, usually the PCB substrate material. This is most commonly noticed on multilayer PCB designs, where the signal trace is equipped with ground planes both above and below it. Due to this arrangement, the high-frequency signal remains inside the PCB leading to fewer emissions and also provides shielding against incoming signals.

The impedance of the stripline is measured in Ohms and can be determined using this calculator by entering Relative Permittivity of the Dielectric, Height of the trace, trace thickness, width of the trace. Additionally, you can also obtain information such as capacitance, propagation delay, and inductance associated with the stripline using this calculator.

PCB Stripline impedence

Understanding Symmetric Stripline Impedance:

Symmetric Stripline Configuration:A flat conductor with the same spacing between it and each ground plane is positioned between two ground planes in a symmetric stripline. The uniform propagation of signals to the reference planes is ensured by this symmetrical arrangement. 

Impedance Calculation: The width, thickness, and distance between the conductor and the ground planes, in addition to the dielectric constant of the material in between, all contribute to the characteristic impedance of a symmetric stripline. 

Applications: High-frequency analog circuits, microwave circuits, and high-speed digital circuits all frequently use symmetric striplines. They are perfect for situations where signal integrity is critical because they offer a balanced transmission line with low radiation and crosstalk. 

Design Considerations: It is crucial to take into account elements like the material’s dielectric constant, the conductor’s thickness, and the separation between the conductor and the ground planes while designing a symmetric stripline. These elements will have an impact on the stripline’s characteristic impedance, which will have an effect on the circuit’s performance. 

Calculators and Tools: To assist designers in determining the characteristic impedance of a symmetric stripline, a variety of calculators and tools are available. Based on the user-provided input parameters, these programs determine the impedance using mathematical formulas and models. 

In conclusion, symmetric stripline impedance is an important idea in the design of microwave, high-frequency analog, and high-speed digital circuits. Using the right tools and calculators, along with an understanding of the elements that determine a symmetric stripline’s characteristic impedance, can assist designers in creating dependable, high-performing circuits.

Substrate Dielectric (e)
Dielectric Height (m)
Trace Thickness (t)
Width of the Trace (w)


\[ z = \frac{60}{\sqrt{e}} \ln \left(\frac{1.92 * (2h + t)}{0.8w + t}\right) \]
\[c = \frac{5.55 * 10^{-11} * e}{ln (\frac {3.81h}{0.8w + t})} \]
\[ p = 3.34 * 10^{-9} \sqrt{e} \]
\[ l = c * z * z \]

where :

  • e = Relative permittivity of the dielectric (Substrate Dielectric)
  • m = Height of dielectric
  • h = Height of trace
  • z = Characteristic impedance
  • w = Width of the trace
  • t = Trace thickness
  • c = Capacitance per unit length
  • p = Effective propagation delay
  • l = Inductance per unit length

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