Advanced Integration Techniques on Broadband Millimeter Wave Beam Steering for 5G Wireless Networks and Beyond
Recently, the desired very high throughput of 5G wireless networks drives millimeter wave (mm wave) communication into practical applications. A phased array technique is required to increase the effective antenna aperture at mm wave frequency. Integrated solutions of beamforming/beam steering are extremely attractive for practical implementations. After a discussion on the basic principles of radio beam steering, we review and explore the recent advanced integration techniques of silicon based electronic integrated circuits (EICs) photonic integrated circuits (PICs) and antenna on chip (AoC) For EIC, the latest advanced designs of on chip true time delay (TTD) are explored. Even with such advances, the fundamental loss of a silicon based EIC still exists, which can be solved by advanced PIC solutions with ultra broad bandwidth and low loss. Advanced PIC designs for mm wave beam steering are then reviewed with emphasis on an optical TTD. Different from the mature silicon based EIC, the photonic integration technology for PIC is still under development. In this paper, we review and explore the potential photonic integration platforms and discuss how a monolithic integration based on photonic membranes fits the photonic mm wave beam steering application, especially for the ease of EIC and PIC integration on a single chip. To combine EIC, for its accurate and mature fabrication techniques, with PIC, for its ultra broad bandwidth and low loss, a hierarchical mm wave beam steering chip with large array delays realized in PIC and sub array delays realized in EIC can be a future proof solution. Moreover, the antenna units can be further integrated on such a chip using AoC techniques. Among the mentioned techniques, the integration trends on device and system levels are discussed extensively.
IEEE Journal of Quantum Electronics