Flip-Chip-Based Dual-Polarized Antenna-on-Package Arrays for 5G mmWave Modules

In this article, we present and illustrate a flip-chip-based antenna-on-package (AoP) concept for the development of 5G mmWave massive MIMO antenna arrays and frontend modules. Unlike conventional Antenna-in-Package concepts, our concept provides the flexibility to choose suitable and separate layer stack-ups and packaging materials for enabling the antennas and the frontend components to meet their respective specifications. To illustrate this concept, we designed, fabricated, and measured novel dual-polarized broadband AoP arrays in the 39 GHz frequency band for 5G mmWave MIMO applications. The array consists of 16 identical stacked patch elements. Each single antenna possesses a driven patch, which is vertically stacked to a parasitic element to improve the antenna performance. It is excited by two orthogonal probe-feds for dual polarization. Furthermore, we designed and optimized antenna arrays together with the solder interconnects used for mounting the antennas onto the multilayered interposer. Our results show that these interconnects could cause up to about 0.5 dB reduction in the realized gain of the antenna array. The fabricated antenna arrays were measured from 33 to 41 GHz. A peak gain of approximately 16 dBi was measured. Excellent correlation was obtained between all the measurement and simulation results.