A Quasi-TEM Approach for Designing Microvias for PCB Layer Transition with Minimal Return Loss

This study proposes an innovative design approach for layer transitions in printed circuit boards (PCBs) using microvia structures. Instead of treating microvias as vertical structures, we approached the analysis of microvias as a segment of a thick planar transmission line using quasi-TEM (transverse electromagnetic) analysis. The proposed design approach is shown to be effective for microstrip to embedded grounded coplanar waveguide (GCPW), microstrip to embedded microstrip, and microstrip to stripline transitions. The fabricated structures have been measured and show excellent return loss performance, achieving better than -15 dB for frequencies up to 150 GHz.