Squint-Free sub-THz Massive MIMO Arrays

Hesham Beshary

EECS Department, University of California, Berkeley

Technical Report No. UCB/

December 1, 2025

To address the growing demand for wireless data capacity, building communication systems at mm-wave frequency bands is one of the primary solutions to realize high bandwidth. Such systems suffer from high free-space propagation losses and technology limitations. Phased arrays are favorable in mm-wave systems as they increase the radiated power directivity and range, and the received signal-to-noise ratio by scaling up the number of array elements. Hence, reducing the cost of building massive phased arrays is required to enable practical high-data wireless links. Additionally, the exponential increase in wireless data traffic is urging the need for improving the energy efficiency of these wireless systems. D-band (110 - 170 GHz) is very attractive due to the available bandwidth and the moderate atmospheric absorption, which can enable short/mid-range high-speed wireless links. Additionally, low-cost CMOS technology has sufficient performance for communications at D-band.

This thesis covers an energy-efficient 2-D scalable transceiver (TRX) phased array with integrated on-chip antennas using low-cost bulk CMOS technology. On-chip antennas allow the use of inexpensive packaging solutions with fewer layers and relaxed requirements and bump spacing. Additionally, the cost and the complexity associated with array up-scaling and integration are significantly reduced. Substrate thinning and substrate-mode cancellation techniques are applied to boost the on-chip antenna radiation efficiency. This work demonstrates 138 Gb/s over-the-air (OTA) using 64-QAM for the overall transmit-receive link while achieving an energy efficiency of 0.33/0.73 pJ/b in RX/TX mode. To date, this is the highest reported array-level OTA data rate and the best energy efficiency (pJ/b) among other D-band arrays by an order of magnitude. The low cost and high level of integration allow building larger arrays to enable multi-user communications and further increase capacity.

Advisors: Ali Niknejad

BibTeX citation:

@phdthesis{Beshary:31888,
    Author= {Beshary, Hesham},
    Title= {Squint-Free sub-THz Massive MIMO Arrays},
    School= {EECS Department, University of California, Berkeley},
    Year= {2025},
    Number= {UCB/},
    Abstract= {To address the growing demand for wireless data capacity, building communication systems at mm-wave frequency bands is one of the primary solutions to realize high bandwidth. Such systems suffer from high free-space propagation losses and technology limitations. Phased arrays are favorable in mm-wave systems as they increase the radiated power directivity and range, and the received signal-to-noise ratio by scaling up the number of array elements. Hence, reducing the cost of building massive phased arrays is required to enable practical high-data wireless links. Additionally, the exponential increase in wireless data traffic is urging the need for improving the energy efficiency of these wireless systems. D-band (110 - 170 GHz) is very attractive due to the available bandwidth and the moderate atmospheric absorption, which can enable short/mid-range high-speed wireless links. Additionally, low-cost CMOS technology has sufficient performance for communications at D-band.

This thesis covers an energy-efficient 2-D scalable transceiver (TRX) phased array with integrated on-chip antennas using low-cost bulk CMOS technology. On-chip antennas allow the use of inexpensive packaging solutions with fewer layers and relaxed requirements and bump spacing. Additionally, the cost and the complexity associated with array up-scaling and integration are significantly reduced. Substrate thinning and substrate-mode cancellation techniques are applied to boost the on-chip antenna radiation efficiency. This work demonstrates 138 Gb/s over-the-air (OTA) using 64-QAM for the overall transmit-receive link while achieving an energy efficiency of 0.33/0.73 pJ/b in RX/TX mode. To date, this is the highest reported array-level OTA data rate and the best energy efficiency (pJ/b) among other D-band arrays by an order of magnitude. The low cost and high level of integration allow building larger arrays to enable multi-user communications and further increase capacity.},
}

EndNote citation:

%0 Thesis
%A Beshary, Hesham 
%T Squint-Free sub-THz Massive MIMO Arrays
%I EECS Department, University of California, Berkeley
%D 2025
%8 December 1
%@ UCB/
%F Beshary:31888