J.J. Rousseau

Fabrication and Measurement of a Coplanar Circulator with 65 µM Yig Thin Film

A circulator with a coplanar structure is designed and analysed using a three dimensional finite element method. Based on the proposed design, the circulator is fabricated with a YIG (Yttrium Iron Garnet). The thickness of YIG is only 65µm. The design is planar and realized by stacking several layers, resulting in a potentially simple and low cost industrial process. Simulated results are better than measured ones but circulation is obtained around 9 GHz. Measured insertion loss is 5 dB and isolation is 36 dB giving interesting perspectives for the device.

Fabrication and characterization of a planar interleaved micro-transformer with magnetic core

This paper presents the design, the fabrication and the characterization of a planar interleaved micro-transformer with an Yttrium Iron Garnet (YIG) core. The design of this micro-transformer and the manufacturing steps are presented. HFSS software is used for the conception and the simulation of the interleaved magnetic micro-transformer. It is composed of two identical windings. A bottom magnetic core is used to improve the integrated transformer performances. To form the windings, we have used a surface micromachining process. We have also used a negative photoresist (SU-8) as an insulating layer and as support for the fabrication of a bridge to connect the central end of the coils to the ground shield. The micro-transformer have been characterized with impedance meter up to 100 MHz, and completed to 1 GHz using vector network analyzer.

Coplanar circulator made from composite magnetic material

This paper deals with the operation of a Y-junction coplanar circulator. It operates at high frequencies (>40 GHz). Barium hexaferrite particles within a host matrix form the integrated magnetic material in this device. The structure of this 3-port microwave device and its different characteristics are presented. A three dimensional finite element method was used to calculate the S-parameters and to evaluate numerically the performance of the circulator. These parameters were measured using a vector network analyzer after the fabrication process showing the performance of the device.

Design and Study of Interleaved and Face to Face Magnetic Microtransformers

The aim of this paper is to compare two types of microtransformers using the High Frequency Structural Simulation simulator. Interleaved and face to face transformers were studied for applications in dc/dc converters and variable speed drive. These transformers have a magnetic material core (yttrium iron garnet) and square spiral windings. The main purpose of the use of magnetic material is to increase the magnetizing inductance LF and the coupling factor k. For this, LF and k were studied by simulation as a function of turn spacing, magnetic, and insulating layer thicknesses. The results presented were compared with recently published works. An important improvement of the main properties was observed in the frequency range (10-100 MHz). The interleaved transformer properties are equal to 0.95 and 0.80 μH for k and LF parameters, which corresponds to an 0.05 μH/mm2 inductance area ratio (LF/A), whereas for the face to face transformer k and LF are equal to 0.9 and 0.78 μH for an 0.08 μH/mm 2 inductance area ratio. Interleaved transformers were manufactured and characterized. Results show close agreement between simulation and measurement results.