Yuko Miyake

Study of exchange-coupled bias field in Ni-Fe/Pd-Pt-Mn thin films

We propose a new Pd-Pt-Mn antiferromagnetic material with high corrosion resistance. This material yields a high Hex to a coupled Ni-Fe film by annealing at a temperature lower than 230/spl deg/C. This material will be suitable for the pinning layer of a spin-valve film and the domain control biasing layer of an AMR head.

A thin film spiral microstrip transmission-line using CoZrNb soft magnetic thin film for a quarter wavelength transformer

This paper examines the possibility of the miniaturization of magnetic/dielectric hybrid transmission-line devices by spiral microstrip transmission-line structure. Since the spiral transmission-line has a mutual inductance between adjacent lines, the wavelength becomes shorter than that of straight line. In this study, a spiral microstrip transmission-line using a CoZrNb soft magnetic thin film was fabricated, and was evaluated.

Suppression of insertion loss by slit patterning of a magnetic film in a CoFeB/polyimide hybrid thin-film coplanar line for a rf impedance matching device

A hybrid thin-film coplanar line with a slit-patterned CoFeB magnetic film for a rf impedance matching was fabricated, and an effect of the loss reduction by introducing a slit-patterned magnetic film was investigated. The fabricated hybrid thin-film coplanar-line device consisted of the top and bottom 5μm thick copper conductors and an inner (0.5μm thick polyimide)/(0.15μm thick CoFeB)/(0.5μm thick polyimide) trilayer. A signal linewidth was 6μm. The total width of the slit-patterned magnetic film was about 200μm. The devices with some kinds of the width of the magnetic film stripe were fabricated. As a result, insertion loss per unit line length decreased greatly above 1.5GHz with decreasing width of the magnetic film. The loss suppression was due to an effect of reducing the in-plane eddy current of the magnetic film. On the other hand, the propagation signal wavelength of the device increased with decreasing width of the magnetic film, which was due to a decrease of distributed inductance. When applyi...

Development of an integrated RF impedance matching device with LPF function using a CoFeB magnetic/polyimide dielectric hybrid thin-film coplanar-line

In this study, the CoFeB/polyimide hybrid thin-film coplanar transmission-line for RF impedance matching was fabricated and its transmission characteristic was evaluated. The device has a thin-film coplanar structure with a CoFeB amorphous magnetic film with a relative permeability of 180, a polyimide dielectric film with a relative permittivity of 3.5, a top and bottom copper conductor film on a glass substrate. The quarter wavelength device with a 100 /spl mu/m width magnetic film consisting of 0.3 /spl mu/m /spl times/ 2 layers had an insertion loss of 2 dB and a line length of 6 mm. The device functioned as a low pass filter with a GHz cut-off frequency, which was due to the eddy current loss and FMR absorption in the magnetic film. Therefore, the hybrid thin-film coplanar-line is expected to apply for GSM cellular phone with non-linear power amplifier.

Fabrication and Evaluation of the Directional Coupler Using CoFeB Metallic Magnetic Film/Polyimide Dielectric Film Hybrid Transmission Line

In this paper, the authors have reported a new directional coupler for the cellular phones with an operating frequency of 0.8-2 GHz, which consisted of a coupled microstrip structure with an amorphous CoFeB magnetic thin film and a polyimide dielectric film.

Analysis of a directional coupler using magnetic/dielectric hybrid transmission-line for cellular phone

Transmission characteristics of a directional coupler with a magnetic/dielectric thin film hybrid structure was analyzed on the basis of 3D electromagnetic field analysis. The device consisted of an inner dielectric/magnetic/dielectric sandwich structure, the top coupled signal lines, coupling capacitance composed of top rectangular electrode, and bottom ground plane. Both electric field coupling and magnetic field coupling between top signal lines were controllable by changing electrode size of coupling capacitance and spacing between top signal lines, respectively. From the numerical calculation of the signal transmission characteristics, an insertion loss was less than 0.6 dB, and signal directivity was more than 15 dB in the frequency range of 0.8-2 GHz used in the cellular phones.