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Number of wavelengths between signal via and ground return vias

Since R2023a



criticalwavelength(via,frequency) returns the number of wavelength between signal via and ground returns vias at a given frequency to analyze for resonant responses or structures. The critical wavelength is given by the equation:



  • d — Center to center distance between signal via and ground via.

  • f — Operating frequency.

  • Er — Relative dielectric constant.

  • c — Speed of light.

You can use this function to quickly determine the maximum wavelength for a given layout. The consequences of exceeding a specified wavelength is given in [1].

criticalwavelength(via,frequency,SignalViaChoic=n) returns the number of wavelengths based on the choice of signal via.


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Calculate the critical wavelength of a single-ended via at 20 GHz.

obj = viaSingleEnded;
tempSubstrate = 
  dielectric with properties:

           Name: 'FR4'
       EpsilonR: 4.8000
    LossTangent: 0.0260
      Thickness: 1.2700e-04
      Frequency: 100000000

For more materials see catalog

ans = 0.2067

Input Arguments

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Single ended via, specified as a viaSingleEnded object.

Frequency to calculate initial wavelength, specified as a scalar or vector integer in Hz.

Choice of signal via, specified as a positive scalar integer.

Data Types: double


[1] Steinberger, Telian, Tsuk, Iyer and Yanamadala, “Proper Ground Via Placement for 40+ Gbps Signaling”, DesignCon 2022, April 2022.

[2] Ramo, Whinnery and Van Duzer, Fields and Waves in Communications Electronics, third edition, section 9.3, John Wiley and Sons Inc., copyright 1994

Version History

Introduced in R2023a