Novel Phased Array Antenna-in-Package Development and Active Module Demonstration for 5G Millimeter-Wave Wireless Communication
5G communication deployment at millimeter-wave frequency range (FR2) has been accelerating in the recent years. Developing a cost-competitive and high-performance RF phased-array front-end system that supports adequate beam-forming and beam-steering capability at 3GPP new radio (NR) FR2 bands is one of the major focus for emerging small-cell base station and CPE devices. In this paper, we will present novel antenna designs and integration methods that enable a low-cost antenna-in-package (AiP) phased-array solution for wireless communication covering 24GHz - 30GHz (N257, N258 and N260 bands). The AiP designs are based on organic substrate technology and support dual-polarization. In contrast to prior antenna-in-package designs for 5G applications , , the proposed AiP structure does not feature an air-cavity which simplifies the fabrication process and reduces the module cost. A total number of 24 antenna design variants were implemented on a 47.5mm x 47.5mm package test vehicle with an element-to-element pitch of 5.9mm. Passive antenna test and characterization were performed extensively in an antenna chamber to measure reflection coefficient, antenna gain as well as radiation patterns. Key measurement results include more than 5GHz antenna bandwidth, 7dBi peak antenna gain with more than 20dB cross-polarization isolation, as well as symmetrical co-polarization radiation patterns at E- and H- planes, respectively. In addition, the AiP test vehicle contains two 16 (4x4) element arrays, one for each main antenna design type. The corresponding antenna feed line structures, signal routing (digital control, IF, LO, etc.), power supplies, and ground are all implemented in the package test vehicle to integrate a 28-GHz SiGe phased array RFIC  for active testing. In the paper, we will also report over-the-air active measurement using the antenna-in-package module including results of spatial power combining, antenna element gain variation, beam-forming, and beam-steering.  X. Gu, et. al., Development, implementation, and characterization of a 64-element dual-polarized phased-array antenna module for 28-GHz high-speed data communications, IEEE Transactions on Microwave Theory and Techniques, pp. 1-10, 2019.  Tung, W.-S.; Chiang, W.-Y.; Liu, C.-K.; Chen, C.-A.; Rao, P.-Z.; Abu, P.A.R.; Chen, W.-M.; Asadi, F.; Chen, S.-L. Low Cost AIP Design in 5G Flexible Antenna Phase Array System Application. Micromachines 2020, 11, 851.  B. Sadhu, et. al., A 28-GHz 32-element TRX phased-array IC with concurrent dual-polarized operation and orthogonal phase and gain control for 5G communications, IEEE Journal of Solid-State Circuits, vol. 52, no. 12, pp. 3373-3391, Dec 2017.