A Wideband Silicon Photonic Millimeter-wave Beamforming Transmitter with Automatic Beam Calibration
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Beamforming with instantaneous wide-bandwidth and high-resolution beam-steering is an essential challenge for many applications including the fifth-generation (5G) wireless communications, radars, and satellite communications such as airborne satellite radios. While it is extremely challenging with conventional electronic beamforming network technology, RF photonics technology has the potential to significantly improve mm-wave beamforming transmitters with wider instantaneous bandwidth, higher resolution in beam-steering, and smaller footprint. Utilizing a photonic beamforming network along with integrated electronics will allow the use of RF silicon-photonics delay units to fulfill these requirements. The project will demonstrate wideband, high-resolution silicon-photonics mm-wave beamforming networks to advance wireless technologies for applications such as wireless communications, radars, satellite communications, and remote sensing. The proposed research has the potential to revolutionize the future of the 5G wireless industries and provide further technological diversification for the semiconductor industry. In addition to the aforementioned technical impacts, the proposed project also promotes outreach activities to increase participation of students from underrepresented groups in science and engineering, including annual summer camps for high school students. The research and educational results of this project will be disseminated to academic, industrial and government sectors. The main goal of this project is to develop a novel chip-scale mm-wave silicon-photonics beamforming transmitter array with wide-bandwidth and high-resolution capability implemented using hybrid Silicon on Insulator (SOI) photonics and Complementary Metal-Oxide Semiconductor (CMOS) chips, along with an antenna array unit. Automatic configuration of silicon-photonics beamforming network using electronic control circuitry implemented on CMOS chip allows for compensation of severe silicon-photonics process and temperature variations in silicon photonics. The proposed research objectives are: 1) architecture definition of a silicon-photonics mm-wave transmitter array with automatic beamforming system and performance analysis, 2) development of novel silicon-photonics beamforming delay units capable of electrical reconfiguration, and algorithms and hardware for delay unit automatic tuning, 3) implementation of novel CMOS prototypes which include the beamforming network tuning hardware, and transmitter front-end circuitry, and testing them with the proposed silicon-photonics integrated circuits, and 4) hybrid integration of silicon-photonics chip, CMOS chip and antenna array unit and perform the required tests for the entire unit. The emerging silicon-photonics technology has enabled the wideband high-resolution RF photonics delay units to be realized for radio systems with small form factor and low power consumption. Furthermore, this project aims to achieve a mm-wave transmitter beamforming array with desired directivity, by precisely controlling a significant number of photonic delay elements inside the beamforming network structure through automatic calibration to provide the desired group delay at the band of interest. The project will also address the degradation of transmitter performance due to inherent non-linearity of photonic modulator devices by linearization techniques that employ integrated RF electronics before the photonic modulator. This award reflects NSF''s statutory mission and has been deemed worthy of support through evaluation using the Foundation''s intellectual merit and broader impacts review criteria.