Results of 2nd period

Summary of the context and overall objectives of the project

Millimetre-wave frequencies are currently being exploited for a wide range of applications such as radars, wireless communication, and imaging. There is a strong industry pull to substantially reduce the cost of mm-wave systems for key markets such as 5G wireless communications and autonomous vehicles (automotive radar sensors). These systems rely on active antenna arrays and electronic beam-steering. A fundamental challenge is to bring into production high performance mm-wave active antenna systems, at a viable price-point and low energy consumption. SERENA aims to substantially increase the functional performance of mm-wave systems as well as significantly reducing their cost. SERENA seeks to maximize the impact by targeting technologies of strategic relevance for European industry and will develop a heterogeneous integration platform enabling scaling of functional performance beyond what is possible in monolithic integration. The platform will be based on breakthroughs in Gallium Nitride on Silicon (GaN-on-Si) technology and state-of-the-art volume packaging. The platform encompasses the whole supply chain; from wafer epitaxy to miniaturised mm-wave systems. Complementary to the integration platform, a hybrid analogue/digital signal processing architecture for optimizing the power efficiency and cost of mm-wave multi antenna array systems will be realised as a proof-of-concept prototype.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved

The project has developed the critical components to build a high-power 5G beamforming radio base station at 39 GHz. Components include fully European integrated RF beamformer and a state-of-the-art monolithically integrated GaN-on-Si front-end have been designed, fabricated, and characterized. A novel packaging low-cost platform for building active antenna modules integrating the developed beamformer and front-end components have also been developed. The project has also worked on concepts for hybrid beamforming architecture for mm-wave radio base stations. The hybrid architecture (combining both traditional analog beamforming with digital techniques) have proven to give better energy efficiency. The SERENA team has also developed an efficient approach to perform coupled electro-thermal simulations of a full communication system. In addition to the work on the 5G proof-of-concept demonstration the project has explored the limits of integration of very high frequency GaN-on-Si integrated circuits. Multifunctional circuits for 90 – 95 GHz including low-noise down conversion receiver and up converting transmitter have been developed. This work has advanced state-of-the-art in terms of integration in GaN technology.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The SERENA project has advanced the available output power for a 39 GHz beamforming system with a factor of 10. This result is based on the characterised output power from the fabricated GaN-on-Si MMIC front-ends. Since the inception of SERENA, 5G mm-wave systems have been commercially deployed in the US (on both the 28 GHz and 39 GHz bands) and other regions have followed. Europe is currently lagging both North America and Asia in terms of mm-wave deployments. Furthermore, 3GPP have ratified the 5G NR standard for sub 6 GHz and above 24 GHz. Mm-wave 5G is already happening and the coming years will give a rapid evolvement of 5G mm-wave radio base station products for various use cases: fixed wireless access, enhanced mobile broadband etc. Ericsson have already launched two generations of mm-wave radio base station products. There is currently a strong market pull which will strongly contribute to the exploitation of the SERENA technology. At the start of the SERENA-project we could not anticipate the rapid deployment of 5G NR technology during the project duration. Main achievements of the SERENA-project are improved TRL of embedding mm-wave RFICs and MMICs in commercial high-frequency laminate printed circuit boards. Both embedding of SiGe RFICs with Cu-pads and GaN-on-Si MMICs with Au-pads have been demonstrated, together with embedding of decoupling capacitors. The TRL for this technology have been increased from 4 to 6. At the start of the project, we had the ambitions target of achieving TRL 7-8 for the integration platform. Based on the experiences in SERENA the consortium has identified the hurdles to move from TRL 6 to 8.