Further cost reduction in today’s microwave
frontends is strongly related to assembly technology as well
as module technology. Depending on the particular mix of
technologies, specific problems and chances can be
addressed. In case of flip-chip on LTCC, various effects of
performance degradation of the MMICs can be observed,
some of which can be related to unwanted internal coupling
of the microstrip IC due to the floating groundplane. For
some MMICs a periodic structure below the chip can help to
improve the characteristics of the assembled chip due to its
ability to suppress a particular class of unwanted modes
between the chip groundplane and the module ground. The
periodic structure is proposed and measured results are
given and discussed
