# criticalwavelength

Number of wavelengths between signal via and ground return vias

Since R2023a

## Syntax

``criticalwavelength(via,frequency)``
``criticalwavelength(via,frequency,SignalViaChoic=n)``

## Description

example

````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: $CW=d*f*\sqrt{\frac{\left({E}_{r}\right)}{c}}$where: 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.```

## Examples

collapse all

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

```obj = viaSingleEnded; criticalwavelength(obj,20e9)```
```ans = 0.2067 ```

## Input Arguments

collapse all

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`

## References

[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