Circuit and antenna-in-package innovations for scaled mmWave 5G phased array modules
Directional communication at millimeter-wave (mmWave) frequencies is one of the key technologies under development towards the anticipated deployment of fifth generation mobile access (5G). Silicon-based multi-antenna systems are strong candidates for the implementation of such directional links; however, the performance requirements are in general significantly more challenging than those posed by mmWave WLAN links demonstrated so far (e.g. for 802.11ad). This work presents an overview of recent innovations in circuit design, antenna design, and beamforming architecture which enable complex phased arrays with precise and agile beamforming for mmWave-based 5G communications. Specifically, this work discusses: (1) a 28-GHz phase shifting transceiver front end, (2) beamforming architecture considerations to enable dual polarized operation as well as multi beam configurability, and (3) two different 28-GHz antenna-in-package (AiP) designs. These advances have been jointly demonstrated in a 64-element dual polarized phased array antenna module (PAAM) consisting of four SiGe ICs and an AiP array. The PAAM supports two simultaneous and independent 64-element beams in either TX or RX modes. PAAM-level measurement results over the air without calibration show +/- 50° beam scanning with >10dB silde-lobe rejection, <1.4° beam steering resolution with 0.6° RMS error, and 54 dBm saturated EIRP in each polarization. On-wafer measurement results from a front-end breakout and a full phased array IC are presented as well.