Simulation and Measurement of PCB Crossover Structures from DC up to 70 GHz

In this paper, 4 different crossover structures in a 6-layered printed circuit board (PCB) for high operation frequencies are presented. The design for all structures is based on grounded coplanar waveguide (GCPW). Two fully planar structures, a quasi-coaxial transition and coaxial transition are realized and have a measured bandwidth from DC to 50 GHz and DC to 60 GHz, respectively. Moreover, two structures are designed in submount technology. Especially the connection between baseboard and package (solder junction) plays an important role to guarantee best signal integrity. Therefore, the quality of the solder junction is analysed in detail with TDR (time domain reflectometry) measurement as well as with X-ray images. The submount transitions show good radio frequency (RF) characteristics from DC to 70 GHz.