Towards Energy-Efficient 5G Mm-Wave links: Exploiting broadband Mm-Wave doherty power amplifier and multi-feed antenna with direct on-antenna power combining

It is envisioned that future 5G wireless links will extensively employ multiple mm-Wave spectra (e.g., 28GHz, 37GHz, 39GHz, and 70GHz). A major bottom neck for silicon-based mm-Wave electronics lies in the generation of mm-Wave signals with high energy efficiency, high linearity, and large modulation bandwidth, all of which are indispensable to support Gbit/s complex modulations with large peak-to-average-power ratio (PAPR) in 5G systems. In this paper, we focus on two technical aspects that recently attract increasing attention and may together address these challenges. We will first present Doherty power amplifier (PA) architecture that offers large back-off efficiency enhancement, linear operation, and low overhead on signal processing. A recent multi-band (28/37/39GHz) mm-Wave Doherty PA in a 130nm SiGe process will be presented as a design example. Next, we will present a new concept of antenna-electronics co-design at mm-Wave. A new “Multi-Feed Antenna” (MFA) is recently proposed and demonstrated by the authors to achieve direct on-antenna low-loss power combining of multiple mm-Wave PAs. A 60GHz all-silicon transmitter design employs on-chip MFA to combine power from 16 PAs and achieves state-of-the-art total radiated output power per transmitter element.