Broadband Characterization of Coplanar Waveguide Interconnects With Rough Conductor Surfaces

This paper presents a method to simulate the effects of conductor surface roughness on conductor-backed coplanar waveguide (CB-CPW) interconnects using 3-D full wave simulation tools. In this paper, a high-frequency structure simulator (HFSS) from ANSYS has been implemented for rough surfaces with Gaussian correlation functions. The rough surfaces that exist between the dielectric and copper foils are modeled using a statistical random process approach. The varying heights for the random rough surface with specified autocorrelation function (ACF), root mean square height (H_rms), and correlation length (λ) are generated using Matlab, and these data are used in HFSS to model and simulate the performance of the CB-CPW interconnect with rough conductor surfaces. The results show that both H_rms and λ influence the overall attenuation coefficient, and the trends are consistent with the other studies in this area. The method presented in this paper provides designers with a technique to characterize the effect of conductor surface roughness for different types of transmission lines with varying substrates and extent of conductor roughness.