Abstract

A general approach is proposed for the accurate and efficient computation of the characteristic parameters of coplanar waveguides having electrodes of complex cross-section on multi-layered, planar or non-planar substrates, as presently considered for high-speed (semiconductor or LiNbO3) electrooptic modulators. The approach is based on the coupling of quasi-TEM finite element method with numerical conformal mapping, and provides the frequency-dependent parameters of an equivalent transmission line model. The present technique, implemented in MATLAB as a practical design tool, is compared with semi-analytical methods (when applicable) and full-wave finite element method: excellent agreement is demonstrated with the full-wave solution, at a fraction of its computational cost.