Trainings and Workshops

The wireless communication industry has been increasing operating frequencies to meet the demand for higher data rates, lower energy consumption, and reduced latency.

Challenges remain in terms of decreased output power and lower efficiency at mm-wave and sub-THz frequencies. While standard Si-based RF-CMOS technology is commonly used due to its cost and ease of integration, III-V semiconductors components such as indium phosphide (InP) hetero-bipolar transistors (HBT), InP high-electron-mobility (HEMT) transistors and even gallium nitride (GaN) HEMTs are better options due to their higher mobility, charge density, and breakdown voltage. The efficiency achievable with these materials results in significant power and area savings for the beamforming transceiver. However, these devices are typically made on small and costly substrates and use processes that are less suitable for high-volume applications. A heterogeneous integration of components from Si-based CMOS and III-V technologies is then crucial.

There are three main challenges to integrate the III-V components into a system. First, the GaN and InP technology back-end stack up has typically a thin gold top level contact pads, which complicate the integration because a standard solder bump flip chip is not possible. Secondly, the III-V technology includes air bridges in the back end.  And at last, the main challenge for the integration is to dissipate the heat generated by the high-power circuit. An embedding PCB-based technology from Fraunhofer IZM was successfully used to tackle these challenges to integrate III-V active components.

This session will present this technology process and its use to integrate a beamforming transceiver using GaN Power Amplifiers at mm-wave frequencies. The design of the package interconnects and integrated patch antenna arrays was based on simulations performed using a 3D full-wave EM simulator (AnsysEM HFSS). The thermal dissipation topic is shown first in simulations with different approaches below the III-V components, to validate the best option to dissipate the heat. This session covers the different aspects of this technology, from technology process to application.