An Extended L–2L De-Embedding Method for Modeling and Low Return-Loss Transition of Millimeter Wave Signal Through Silicon Interposer

This article presents a new modeling and optimization approach for low return-loss transition of millimeter wave signals in flip-chip die-to-die interconnects using silicon interposer technology. The L –2 L de-embedding method is used and extended by carefully selecting appropriate structures and designs to model and characterize micro/millimeter-wave bumps and vias. Initially, the L –2 L method is employed to analyze microstrip line die-to-die interconnects, including trace and microbumps. Subsequently, the L –2 L de-embedding method is extended to examine the stripline signaling scheme and extract the model of vias. It is shown that the proposed approach can extract the model of stacked vias between the different layers of a silicon interposer stack-up. Also, the adopted method is utilized to analyze various parts of the transition in the case-study signaling schemes with ground shields. The validity of the proposed strategy is verified by employing the commercial full-wave simulation tool Ansys HFSS to analyze die-to-die interconnects at different stages. The effectiveness of the method in optimizing test structures is also investigated, with the optimized structures exhibiting insertion losses below 1 dB and return losses better than 25 dB from dc to 60 GHz. Using the proposed modeling method provides room for significant improvements in the prelayout design stages.