Regarding Arc routing

1. Reduces reflections on the signal ,by minimizing impedance discontinuities.
2. Creates equal-length traces.


SATYA SHANKAR.G
AT&S ECAD Technologies Pvt. Ltd.,

If we set some impedance for one trace, the impedance should be same through out the trace.

It is not possible to maintain the same impedance at the corners if we take 45 or 90 degree traces as the cross section will be different at the corners (take right angle triangle corner trace width will be sq.root of adjuscent side and opposite side).

To perfectly match the impedance we need to go for ARC routing.


All the best..
Sriram

Hi All,

I'm starting to laugh again. Thanks. Been in the PCB design trade ~20 years, and how many curved traces have I done? Probably ~12 lines... total. Done designs up to 10Ghz, and still 45 degree corners. Impedance is predominately controlled by your stackup (e.g. materials, dielectric thicknesses, layer placement). There is little discontinuity wth 45 degree corners unless you're working ultra-fast circuits or RF/Analog design. Yes, I have done curved traces on RF designs. Not many though.

Last question. If you're really concerned with discontinuities ("perfect matching"), what do you do with the case of vias on the traces? That would be a major disruption, because you're creating a 90 bend, right? So do you do? No vias allowed?

If you want the answers to something as fundamental as impedance, takes 1-2 hours (spare time), and investigate what the internet (google, yahoo, etc.) has to offer.

Howard Johnson - signcon.com
Lee Ritchey - speedingedge.com
Ultracad.com (look at their 90 degree section. :)
everythingPCB.com (great site)

Good day.
Mitch