A wide-band microstrip-to-microstrip multi-layered via transition using LTCC technology

A wide-band microstrip-to-microstrip via transition used for connecting integrated circuits and antenna array in a multi-layered low-temperature co-fired ceramic substrate is investigated in this paper. The via transition is decomposed into external and internal segments to facilitate the design. The equivalent impedance of internal segment, consisting of multi-layered through-hole via with four ground vias, is calculated from the lump-circuit model generated by Ansoft Q3D Extractor. The electrical performance of the external segment, consisting of via to microstrip lines, is evaluated by the microstrip-to-coax transition to choose appropriate via physical parameters. Finally, the geometrical parameters of entire transition are obtained by combining the results of the external and internal segments. It has been demonstrated, through the simulation results by commercial software Ansoft HFSS, that the return loss is better than 19 dB over a band from DC up to 70 GHz with an in-band insertion loss better than 0.48 dB.