UC Santa Barbara

Future trends in wireless communication systems show rapid growth in mobile data traffic. The number of subscribed users per mobile base station grows linearly with time. Emerging immersive media formats and applications (i.e., HD/UHD, 360 videos, AR/VR) requires a higher data rate and larger channel bandwidth. Millimeter-Wave massive multiuser multiple-input multiple-output (MU-MIMO) is a potential candidate for high-capacity, high data rate wireless base stations. The available mm-wave spectrum between 100GHz to 300GHz is large. The small carrier wavelength (λ) permits compact arrays with many antennas; hence spatial multiplexing can be utilized to increase the system capacity.

This thesis explores system architectures, transceiver circuit design, and high-performance packaging technologies suitable for mm-wave and sub-THz multiuser massive MIMO arrays. First, we present a comprehensive study between potential mm-wave MU-MIMO architectures (all-digital, hybrid, and fully-RF) in terms of system dynamic range requirement. We draw guidelines on the required system front-end 1-dB compression point and the required analog-to-digital converter resolution for each architecture. We also illustrate the impact of system power control and antenna load factor on relaxing the dynamic range requirements.

Next, we present the core elements for our massive MIMO arrays. We designed and tested a single-channel direct conversion transmitter (Tx) and a single-channel direct conversion receiver (RX) using Global-Foundries 22FD-SOI technology, with a record measured 3-dB modulation bandwidth of 20GHz. The Rx has 27dB conversion gainand -30dBm P-1dB. The Tx has a saturated output power (Psat) of 3dBm. Then, we used those transmitter and receiver chips and demonstrated two different packaging technologies in building our mm-wave MU-MIMO arrays. We designed, fabricated, and tested tiles of 8-elements transmitters/receivers, integrated with an on-package series fed patch antennas, assembled on high-performance laminate material and on Kyocera low permittivity ceramic interposer. We illustrate the pros and cons of each packaging technology and show the superiority of the ceramic interposers for mm-wave applications and highly dense arrays.

Finally, we integrated our MU-MIMO transmitter/receiver tiles with Xilinx ZCU111 FPGA and demonstrated the world’s first mm-wave MU-MIMO arrays at 135GHz. Our transmitter MU-MIMO array has a record transmitter effective isotropic radiated power of 39dBm, a field of view of +/-15 degrees. It can support a wide range of modulation schemes (i.e., QPSK, 16QAM). The integrated transmitter and receiver MU-MIMO arrays can be used for a broad range of applications, including single beam and multibeam phased arrays, wireless backhaul, imaging, and radar applications.