1/4 for Digital Paths
1/12 for RF Paths
1/16 for Analog Paths
Use the Saturn PCB Toolkit v7.05 to calculate lumped / distributed wavelengths.
Note that 1/Time = Freq and 1/Freq = Time, they are reciprocals.
In the Saturn PCB Toolkit select the Wavelength Calculator tab.
Example:
Select the Period to enter the edge rate transition time.
Enter 1nS for the Risetime period. (10% to 90%)
Enter the Er Eff (effective Er (Dk) Dielectric Constant.
Set Wavelength Divide to 1/4 Wave Length.
click on image to view
As shown above the distributed 1/4 wavelength = 1.46 inches for a rise time of 1 nS.
Paths shorter than this length are lumped lengths and longer lengths are distributed length paths. Distributed lengths should be impedance controlled paths.
Something for the RF Geeks: Quarter Wave Tricks
Something for Everyone: Admiral Grace Hopper Explains the Nanosecond
Who is Grace Hopper? - YouTube
That's it !
