This paper presents a broadband microwave vertical transition structure suitable for System on Package (SOP) applications at millimeter-wave frequencies (mmW). The designed structure includes a Microstrip (MS) to Stripline (SL) back to back vertical transition optimized for 60 GHz applications but also suitable for E-band frequencies as well. The mmW transition presented here was fabricated in a Low-Temperature Co-fired Ceramic (LTCC) process using commercially available Ferro A6M tape layers. Design and optimization of this microwave transition was carried out in order to maintain a constant characteristic impedance over the entire bandwidth. A bandwidth improvement of 30% is observed by optimizing the ground via fence of the vertical transition. A maximum of 12 surrounding vias were used due to limitations in the LTCC process. Measurements of this vertical transition show a Return Loss of better than 10 dB for frequencies as high as 90 GHz while maintaining an insertion loss of less than 0.9 dB. A grounded coplanar waveguide (CPWG) to MS planar transition with good electrical performance for up to 110 GHz was also designed and implemented to characterize the vertical transition fabricated.

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Conference 13th European Microwave Week 2010, EuMW2010: Connecting the World - 40th European Microwave Conference, EuMC 2010
Amaya, R, Li, M. (Ming), Hettak, K. (Khelifa), & Verver, C.J. (Cornelius J.). (2010). A broadband 3D vertical microstrip to stripline transition in LTCC using a quasi-coaxial structure for millimetre-wave SOP applications. In European Microwave Week 2010, EuMW2010: Connecting the World, Conference Proceedings - European Microwave Conference, EuMC 2010 (pp. 109–112).