| Biography | |
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 Dr. Vincent Laur Lab-STICC laboratory, France |
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| Title: Toward miniaturized integrated andlow-cost circulators and isolators | |
| Abstract:
Microwave circulators and isolators are currently used in RF front-ends to protect devices that are sensitive to variations of power levels, such as amplifiers, from impedance mismatches. These devices are also often used in full-duplex systems when a single antenna is used. However, these devices are mainly fabricated by hybrid technologies (insertion of ferrite pucks in a triplate or microstrip structure) leading to high bulkiness and cost. Furthermore, bulkiness is exacerbated by the need for permanent magnets to polarize the ferrite pucks. Indeed, mass production of low-cost compact circulators remains a hot topic and new ideas and technologies are needed to improve the integration of these devices.
Removing the magnets appears to be a way to decrease circulator size. This can be achieved by the use of pre-oriented hexaferrites, especially M-type strontium hexaferrites. Indeed, these materials make it possible to keep a strong magnetization without applying an external magnetic field. Experimental demonstrations will be presented in this talk. However, this concept is mainly limited to millimeter-wave frequencies (even if some demonstrations were realized at frequencies as low as 10 GHz) due to the high anisotropy field of these ferrites.
At lower frequencies, some technological means make it possible to increase the integration and to decrease the cost of circulators. Recently, substituted Yttrium Iron Garnet (YIG) ferrites were developed in order to be compatible with a Low Temperature Co-fired Ceramics (LTCC) process. A sintering temperature of 880°C can be achieved by using Vanadium and Bismuth substitutions, while keeping dielectric and magnetic properties compatible with the realization of microwave circulators. Experimental demonstrations of X-band (8-12 GHz) circulators in LTCC technology will be presented. As this technology allows co-sintering ferrite, dielectric and metal in a unique step, it appears to be a promising way to decrease the cost of these components.
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| Biography:
Dr. Vincent Laur received his M. Sc. Degree in Sciences and Technologies of Telecommunications from the University of Brest, France, in 2004. In 2007, he received his Ph. D. Degree of Electronics from the University of Brest, France. In 2008, he was a post-doctoral fellow at XLIM laboratory, Limoges, France, where he worked on ferroelectrics- and MEMS-based tunable devices. He is now an Associate Professor in the functional materials team of the Lab-STICC laboratory, University of Brest.
His research activities are focused on the characterization, modeling and integration of functional materials (ferroelectrics, ferromagnetics, ferrites…) in microwave devices. He is also invested in the application of new technologies (3D printing, 3D metallization, Molded Interconnect Devices, nanomaterials…) to the microwave domain. He is currently involved in two European projects and several industrial contracts (CNES, Thales Alenia Space) in the space domain. Since 2005, he is the co-author of more than 70 papers in journal and international conferences.
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