Coplanar traces are common in printed circuit boards. Coplanar traces where one trace is the signal and the other trace is the return path apply to this inductance calcualtor.
The inductance of the coplanar trace calculation requires 4 variables:
This structure requires that these spacings be uniform down the entire length of the trace.
The inductance of the coplanar trace is:
L_{coplanar}\approx \frac{\mu _{o}\mu _{r}}{\pi}\cosh^{-1}\left ( \frac{s}{w} \right )
where
\left ( d>>w, w>t \right )