Heterogeneous Integrated Sub-THz Transceiver Frontend
Prof. James C. M. Hwang
Cornell University, Ithaca, New York 14853 USA
Heterogeneous integration of different kinds of chiplets on an interposer has been developed for digital and memory applications. Heterogenous integration for RF applications is just emerging. In this case, with only a few input/output channels, there is plenty of room in the bulk of the interposer for passives such as combiners, filters, duplexers, and antennas that are much more efficient than their thin-film counterparts. This makes it possible to have a complete RF frontend on an interposer. In particular, at sub-THz frequencies (100-300 GHz), substrate-integrated waveguides (SIWs) can have much lower loss than microstrip or coplanar transmission lines. With the signal fully enclosed in the SIW, transmit and receive channels can be placed next to each other without crosstalk. Thus, a linear phased array, with each transceiver confined to a half wavelength, can be fabricated on the same interposer. In turn, the interposers can be stacked to form a 2D end-firing array. These points will be illustrated through the GaN-on-SiC technology. However, similar heterogeneous integration approaches are applicable to other device technologies and interposer materials.