SURFACE-MOUNT monolithic-microwave-integrated- circuit (MMIC) packages must contain high-performance vertical transitions. Usually, such a transition will use viaholes, which act as an inductance and generates a discontinuity. In contrast, Inkwon Ju, In-Bok Yom, and Seung-Hyeub Oh from ETRI's Satellite Communications RF Technology team have proposed a vertical transition that utilizes a trough line, slab line, and shielded multilayer coplanar waveguides (SMCPWs). This novel transition has made possible the development of a low-loss, low-temperature-co-fired-ceramic (LTCC), hermetic surface-mounting MMIC package with bandwidth of DC to 50 GHz.

For its construction, the vertical transition leverages the multiple transmission lines of the trough and slab lines. From DC to 53 GHz, the manufactured LTCC hermetic surfacemounting MMIC package showed an insertion loss of less than 0.6 dB and a reflection loss of under -20 dB. See "Low Loss DC to 50 GHz LTCC SMT Package for Millimeter Wave MMICs," Microwave And Optical Technology Letters, Jan. 2008, p. 24.