Quote Originally Posted by Tony_Montana
What configuration is face to face? The most ribbon cables I have seen are edge to edge to make them thin and "ribbon" like
Given two ribbons half inch wide and 25 mils thick..

Side by side makes it one inch by 25 mils, that is what you considered ribbon.

Face to face makes it half inch wide, and 50 mils thick.

Ribbons can also be like the type used in computers..the cables that go to internal hard drives..they are lots of round wires side by side..some ribbon speaker cables are made by alternating conductors pos and neg. In essence, it takes the inductance of a pair of those wires, and parallels them..one pair, with say, .2 uH per foot, 50 pairs in parallel would be 200 nH divided by 50, or 4 nH per foot. (yah, I know this is very simplistic, as pair to pair proximity will also drop the inductance total..but the flavor is better kept by keeping the explanation simple.) Capacitance increases at about the same rate..

Cheers, John