As 5G rolls out worldwide, teams of visionary experts are developing roadmaps and use cases for the next generation wireless network: 6G. They have mapped socially valuable and commercially promising opportunities that cannot be achieved with the bandwidths available in the 5G spectrum below 90 GHz. The road to 6G requires the development of wireless transceivers operate in the spectrum above 90 GHz, that is known as upper millimetre-wave (Umm-Wave) region, with peak data rates approaching a terabyte per second (1Tbs).
At present, the rapid progress in mm-Wave integrated circuits (ICs) have already paved the way for electronic products in lower mm-Wave frequency, including phased-array transceivers operating at 24/28/39-GHz bands for cellular network, 60-GHz band for high- speed Wi-Fi, E-band for back-haul system and 77-GHz band for automotive anti-collision radar, just to name a few. These solutions are the hardware foundation of the current 5G technology, as they support multi-gigabit communication as well as low-latency real-time sensing services and will continually play a critical role for the 6G era. There is no doubt that the mm-Wave ICs design will remain to be one of the very popular research topics within the Circuits & Systems Society.
Although the spectrum allocated for 6G has not finalised yet, it is very clear by now that the spectrum between 90-300 GHz will be used for the 6G era, especially the so-called D- band (110-170 GHz). To exploit spectrum above 90 GHz, 6G must address the challenge of scattering and absorption in the ambient environment that leads to substantial path loss compared with the spectrum below 90 GHz. This is an extremely pressing problem, which can only be solved through a combination of multiple breakthroughs, from novel circuit design techniques to advanced packaging technologies.