I’ve got a few questions about this topic. What is this squiggly trace on this pcb, whats it for, and how could I create something like this on Eagle PCB?
It’s to equalise track lengths for high-speed signals, it’s called serpentine routing. Those tracks look like a differential pair, which need to be the same length.
The Pulsonix software I use will do it automatically for me, calculating the track length, within preset limits. I don’t know if Eagle can do it.
Nope… Eagle doesn’t automate that for you. There’s an ULP that calculates trace length (length.ulp / length-freq-ri.ulp), so you could manually do it if there isn’t an ULP that does it for you (I don’t recall seeing one). I would guess that an ULP could be made to introduce serpentine on an existing trace to match another one, as well - it’s within the realm of the code’s possibilities at least.
Once trace lengths start mattering in terms of timing issues, though, I’d say you need to look at the upper-level packages.
If you did want to do it manually, the ‘Bend a line’ tool (command SPLIT) is the easiest to use, just set up a fine alternate grid and hold the Alt key while ‘bending’ the line, clicking around to make that serpentine pattern. For just a few traces, it’s not so bad.
In most cases, equalizing lengths like that is going overboard. In the example given, there would probably be a fraction of a millimeter difference in track lengths if they didn’t do the “squiggly” equalization. You’d need to be operating at much more than a GHz for this to be a problem.