In wireless communication, with 5G as the next generation, there is a push towards higher operating frequencies, moving from the congested sub-6GHz bands towards mm-wave bands (and beyond). The introduction of these mm-wave bands has a significant impact on the overall 5G network infrastructure and the mobile devices. For mobile services and Fixed Wireless Access (FWA), this translates into increasingly complex front-end modules that send the signal to and from the antenna. To be able to operate at mm-wave frequencies, the RF front-end modules will have to combine high speed (enabling datarates of 10Gbps and beyond) with high output power. In addition, their implementation in mobile handsets puts high demands on their form factor and power efficiency.
Beyond 5G, these requirements can no longer be achieved with today’s most advanced RF front-end modules that typically rely on a variety of different technologies amongst others GaAs-based HBTs for the power amplifiers – grown on small and expensive GaAs substrates.
“To enable the next-generation RF front-end modules beyond 5G, imec explores CMOS-compatible III-V-on-Si technology”, explains Nadine Collaert, program director at imec. “Imec is looking into co-integration of front-end components (such as power amplifiers and switches) with other CMOS-based circuits (such as control circuitry or transceiver technology), to reduce cost and form factor, and enabling new hybrid circuit topologies to address performance and efficiency.
Imec is exploring two different routes: one is Indium Phosphide (InP) on Si, targeting mm-wave and frequencies above 100GHz (future 6G applications) and the other is GaN-based devices on Si, targeting (in a first phase) the lower mm-wave bands and addressing applications in need of high power densities. For both routes, the researchers have now obtained first functional devices with promising performance characteristics while identifying ways to further enhance their operating frequencies.