626 B
626 B
title, created_date, updated_date, aliases, tags
| title | created_date | updated_date | aliases | tags |
|---|---|---|---|---|
| PCB Design Review | 2025-02-12 | 2025-02-12 |
PCB Design Review
Rise Time vs Length
The rule of thumb is that a track length shall be shorter than 1/6th of the rise time. According to this comment the rule of thumb can be applied like this (example with 100MHz signal): First lets calculate the wave length in free space:
\lambda = \frac{c}{f} = \frac{3*10^{8}}{100*10^6} = 3m
In a PCB you can take roughly \frac{\lambda}{2} as the wavelength, which would be 1.5m.
One sixth of this results in roughly 25cm.