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Fujikura Technical Review

No.52 February, 2023

ISSN 2436-9268
ISSN 0388-225X
Published by :
Fujikura Ltd.
1-5-1, Kiba, Koto-ku, Tokyo 135-8512, Japan


160-µm Coating Optical Fiber for 1728-Fiber Cable

Along with the explosive growth in broadband services and data center market, optical cables with high fiber density and reduced diameter will be more demanded. A thin coating fiber is an attractive solution for realizing a high density and reduced diameter cable. In this study, we fabricated a 1728-fiber cable using 160-µm coating fiber with 80-µm cladding. This cable realizes 26% reduction in cable diameter and 42% lighter in weight while comparing with a cable with 250-µm coating fibers and shows good attenuation characteristics over wide range of temperature and satisfies general requirement for optical fiber cables.


Multi-fiber Hardened Optical Connector Suitable for 5G Optical Network Infrastructure

In recent years, with the spread of network services such as 5G, simpler optical connection work is required. Generally, working skill and experience were required because optical connections in optical termination boxes or optical closures were made by fusion splicing or field installable connectors. Therefore, we have developed a multi-fiber hardened optical connector for outdoor use that is compact and has excellent connection workability. The developed product has a uniquely designed connector structure, which makes it compact, yet has robust mechanical characteristics, and is also excellent in waterproofness. The optical characteristics, mechanical characteristics, and waterproof characteristics of the prototype were evaluated and confirmed to be excellent.


Over-The-Air Tests of Phased Array Antenna Module for 5G 28 GHz band

In response to the emerging 5G New Radio (NR) millimeter-wave technology, we have developed our state-of-the-art Phased Array Antenna Module (PAAM) named “FutureAccessTM”, with robust performance at 28 GHz band. The PAAM integrates an Array Antenna, Beam Former ICs (BFICs), Frequency Conversion IC (FCIC), Band-Pass Filters (BPFs) and Power Combiners/Splitters (COMB-SPLITs). The performance of millimeter-wave band devices must be evaluated at Radiation Interface Boundary (RIB) as per 3GPP specifications. We have confirmed the PAAM’s performance characteristics in the Over-The-Air (OTA) tests conducted at our facility in Fujikura.


28 GHz Band High Linearity Frequency Conversion IC for 5G Mobile Communication Systems

Phased array antenna modules can benefit from scalability, configurability and Si area efficiency by splitting beamforming and frequency conversion functions between separate ICs. This paper introduces a frequency conversion IC having high-linearity and architectural features that enables to support dual-polarized, scalable phased arrays with >64 antenna elements for the mm-wave 5G systems.


Over-the-Air Testing on Millimeter-Wave Communication Modules

This paper describes over-the-air (OTA) testing methodology used for the performance evaluation of millimeter-wave (mmWave) communication modules. First, the reason why OTA testing is indispensable for characterizing mmWave communication modules is explained. Next, a basic configuration for OTA testing is illustrated. And two important performance metrics obtained in OTA testing are described. They include equivalent isotropic radiated power (EIRP) and equivalent isotropic sensitivity (EIS). Furthermore, the actual EIRP and EIS results measured in an OTA testing system for 60 GHz band mmWave communication modules are provided. These results are important parameters that are directly related to the quality of wireless communication links in the field application.


Flexible Circuit Board Package Embedded with Multi-stack Dies

Miniaturization of electronics modules is always required for various medical applications such as wearable and implantable devices. Embedded die technology is one of the promising technologies to realize miniaturization and high-density packaging. We have developed Wafer And Board level device Embedded (WABE) technology for embedding dies into multilayer flexible printed circuit (FPC) boards. This WABE technology has enabled multiple dies to be embedded by the one-step lamination process and the footprint of a package can be reduced drastically by embedding multiple dies vertically in stacks. This paper describes the details of the results of fabricating a test vehicle with six embedded dies (three-dies in two stacks side-by-side).