De-embedding transmission line measurements for accurate modeling of IC designs

Abstract

A new technique to de-embed the contributions of parasitic structures from transmission line measurements is presented and applied to microstrip lines fabricated in 90- and 130-nm RF-CMOS technologies. De-embedded measurements are used to extract characteristic impedance, attenuation constant, group delay, and effective permittivity. The effective thickness of the ground plane is demonstrated to be as important as the thickness of the top metal layer in minimizing interconnect loss. Furthermore, it is confirmed that metal area densities as low as 65% are adequate for the ground plane of microstrip lines.