Wideband LTCC transitions of flip-chip to waveguides/connectors for a highly dense phased array system-in-package at 60 GHz

This paper presents two types of wideband transitions from a flip-chip interconnect to external v-band rectangular waveguides and surface-mount coaxial connectors, based on LTCC technology. The flip-chip interconnect is directly connected to a multi-level stacked via allowing compact routing of RF signals for a highly dense phased array system-in-package. The signal is guided from striplines into the waveguides using a T-shape launcher and impedance matching is performed by several means including implementing a stub and tapering a near-quarter wavelength embedded waveguide. In the other design, mm-wave signals are directed from a stripline to a surface-mount 1.85 mm v-type connector to provide a compact solution for multiple input/output transceivers. Both types of transitions are fabricated and initial measurement results are presented. Compactness and low loss (0.5 dB) performance along with over 20 % bandwidth from 55 to 67 GHz make the transitions suitable for 60 GHz WiGig applications.