Universal Spectrally Agile and Energy Efficient Non-periodic Arrays and Transmitter Architectures at Millimeter-Wave Band

Abstract

The evolving spectral allocations in the mmWave bands across 30-100 GHz for 5G beyond creates interesting opportunities for communication and sensing across licensed/unlicensed bands. Wireless interfaces can benefit tremendously from being able to flexibility operate in any part of these spectrums. Such a universal front-end can serve as the ultimate interface for communication or sensing for intelligent spectrum sharing or for joint operation. Phased arrays, that are the fundamental unit of these wireless interfaces that allow the beamforming ability. These arrays are constituted with arrangement of antennas that are periodically placed, typically spaced at half the operation wavelength, each interfacing with transceiver architecture with phase control. However, such arrays are fundamentally limited in their frequency range of operation because 1. It is extremely challenging to realize broadband transmit/receive circuitries (especially power amplifiers) that are of high performance. 2. The element spacing creates spatial aliasing when the spacing exceeds half a wavelength. 3. The antennas are typically resonant at the frequency of operation and cannot operate as broadband array antenna. The vision of this thesis is of a universal mmWave array interface and constituent circuits that can efficiently operate at ultra-wideband frequency range (30-100GHz). To this end, we propose 1. Multidimensional (device, architecture, and methodology) techniques for mmWave broadband and high-efficiency PAs in various IC processes. Innovative ideas include stacked common base PA cells, mmWave harmonic engineering, non-Foster impedance synthesis for high back-off efficiency over wide frequency range, and deep learning-enabled PA inverse design methodology. Such broadband PAs also support concurrent multi-band operation, capable of achieving higher data rates and quality of service. 2. Fundamental design and optimization strategies toward an aperiodic sparse antenna array geometry, capable of operating across ultra-wide frequency ranges while overcoming the trade-offs among directivity, inter-element coupling, and grating lobe issues. 3. Design for the first time: an ultra-wideband (90% bandwidth) transmitter phased array system, with design highlights in broadband blocks such as phase shifter, on-chip passives, upconverter, and broadband antenna. A universal array aperture can transform the operation of arrays allowing intelligent spectrum sharing, control and management for future wireless communication and hyper-spectral sensing and imaging.