Off-Chip Coaxial-to-Coplanar Transition Using MEMs Trench

This paper presents the electromagnetic Finite Element Analysis (FEA) of a novel chip-to-chip interconnect for use in System-in-Package (SiP) applications. An on-chip coplanar transmission line is transitioned to an off-chip coaxial cable using an etched trench on Silicon. This approach to die-to-die signaling has inherent advantages over traditional wire bonding that include matched impedance, shielded signal conductors, and low impedance return paths. This paper presents the analysis of the impedance discontinuities associated with the transition between the two controlled impedance structures (coplanar and coaxial) in order to understand if the manufacturing processes used affects the ideal operation of this structure. We show that this type of die-to-die interconnect system reduces the parasitic inductance of the signal path by 57% and that reflections are reduced by 75% compared to a traditional wire bond.