Although there are plenty of free impedance calculators out there, I'm struggling to find one that can solve impedances for a differential pair using coplanar waveguide. Anyone know of any free software that can do that? The only one I was able to find was Si9000 and Si8000m by Polar instruments, but they aren't free.
Reason I'm interested is because I'm trying to route USB 2.0 HS signals on a 2 layer 1.6mm FR4 board and want to see if using coplanar waveguide will make it more practical (i.e. thinner traces).