S-Parameter-Based Modal Decomposition of Multiconductor Transmission Lines and Its Application to De-Embedding

Theory and experiments are presented of modal decomposition of scattering matrices of multiconductor transmission lines (TLs). In effect, n coupled TLs are decomposed into n independent ones. Its use is demonstrated by applying it to thru-only de-embedding of 4 coupled TLs (synthesized data) and 2 coupled TLs (measurement data from a 0.18 μm-CMOS chip). The proposed de-embedding method could greatly facilitate accurate characterization of on-chip multiport networks.