Symmetric Stripline Impedance Calculator

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This calculator helps you compute the characteristic impedance of a symmetric stripline.

Inputs

Trace Thickness

oz/ft^2 mil cm mm um inch

Substrate Height

mil cm mm um inch

Trace Width

mil cm mm um inch

Substrate Dielectric

Output

Impedance

Ohms

The Symmetric Stripline Impedance Calculator is a tool designed to calculate the characteristic impedance of a symmetric stripline, which is a common transmission line structure in high-frequency PCB design. The characteristic impedance is a critical parameter that affects signal integrity and performance in RF and high-speed digital circuits.

Inputs:

1. Trace Thickness (t):
   • The thickness of the conductive trace, typically measured in mils or micrometers.
2. Substrate Height ($h$):
   • The distance between the ground planes, which also corresponds to the height of the dielectric material separating the trace from the ground planes.
3. Trace Width (W):
   • The width of the conductive trace.
4. Substrate Dielectric Constant (ϵr):
   • The relative permittivity of the dielectric material (substrate) used in the stripline construction.

Output:

• Impedance (Z0​):
  • The characteristic impedance of the symmetric stripline, calculated based on the inputs.

Symmetric Stripline Impedance Formula:

The characteristic impedance of a symmetric stripline can be approximated by the following empirical formula:

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Where:

• h = Substrate height (distance between the ground planes)
• W = Trace width
• t = Trace thickness
• ϵr = Relative permittivity (dielectric constant) of the substrate

How to Use the Calculator:

1. Enter the Trace Thickness (t): Provide the thickness of the conductive trace in the stripline.
2. Enter the Substrate Height ($h$): Input the height of the substrate between the ground planes.
3. Enter the Trace Width (W): Provide the width of the conductive trace.
4. Enter the Substrate Dielectric Constant (ϵr​): Input the relative permittivity of the dielectric material.
5. Calculate Impedance: The calculator will use the above formula to compute the characteristic impedance of the stripline.

Why It Matters:

The characteristic impedance is crucial for maintaining signal integrity, especially in high-frequency and high-speed digital circuits. Mismatched impedance can lead to signal reflection, loss, and degradation, affecting the overall performance of the circuit. This calculator helps designers optimize the physical dimensions of the stripline to achieve the desired impedance, ensuring efficient signal transmission.