A Wideband Physics-Based Model for Coplanar Waveguides With Redistribution Layer Process

An accurate equivalent circuit (EC) model of coplanar waveguides (CPWs) with redistribution layer (RDL) process is crucial for 3-D integration interconnections design. This study proposed a physics-based EC model containing the key geometric and material parameters such as the gap, width, permittivity, and bulk conductivity. Besides, an improved substrate effects model, which will induce obvious resonances in high frequency over 60 GHz, is proposed for CPW and ground CPW (GCPW). The proposed model is first validated with various CPWs by full-wave EM simulation with good accuracy up to 400 GHz. Then, the model is validated by measured results from 100 MHz to 110 GHz. The results show that the relative root-mean-square error (RRMSE) of the model can reach less than 10% compared with measured results. The proposed model will be useful in designing high-speed circuits based on the RDL process at millimeter waves.