A Demonstration of a Wideband Low-Complexity Multibeam Analog Beamforming Network

This work proposes using a sparse factorization of the multibeam delay Vandermonde matrix (DVM) for reducing the complexity of multibeam analog beamformers. The example of a proof-of-concept sparse-factorized DVM theoretically requires only 70 of unit true time delays (TTDs) to implement four beams with eight antennas, compared with the 252 unit TTDs required in conventional implementations. The number of TTDs was further reduced to 65 by simplifying the signal-flow graph (SFG). A proof-of-concept integrated multibeam radio-frequency (RF) beamformer is discussed. It utilizes TTDs to realize four simultaneous beams to cover a spatial area of 0° to 60°. To demonstrate the concept, a prototype of the proposed four-beam beamformer was fabricated in a 22-nm fully depleted silicon-on-insulator (FDSOI) CMOS process. This proof-of-concept prototype operates from 1.6 to 5.6 GHz, occupies a chip area of 0.37 mm2, uses 58 current-mode unit TTDs, 27 current-mode adders, and consumes 3.7 mW/channel of dc power. This simplified approach to realizing multibeam networks has the potential to enhance the implementation efficiency in analog and hybrid beamforming systems, including multi-input multi-output (MIMO) arrays, 5G and 6G arrays, and SATCOM arrays.