S. Tanabe

IEEE 1901 access system: An overview of its uniqueness and motivation

In 2005 the IEEE P1901 Working Group began standardization activities for broadband over power line networks. The process is now in its final stages, and the latest P1901 draft standard is available for sale to the public. The standard is designed to meet both in-home multimedia and utility application requirements including smart grid. The utility requirements and the resulting features that support those requirements were clustered together and form the basis of what is referred to as the utility access cluster. This article explains the aspects of P1901 power line communication technologies designed to address the access cluster. The differences between access and in-home applications, including addressing methods, clock synchronization, smart repetition, quality of service, power saving, and other access unique mechanisms, are also explained.

Improved RF integrated magnetic thin-film inductors by means of micro slits and serface planalization techniques

Improvement of magnetic thin-film inductors for RF monolithic microwave integrated circuits (MMICs) is discussed. Surface planarization reduced the surface roughness down to R/sub a/=1.2 nm, which enhanced the quality factor by 14% over a nonplanarized inductor. The orthogonal bar slit pattern was the best among the fabricated slit patterns, L=7.55 nH (+12% of the air core), R=6.80 /spl Omega/ and Q=7.09 (+9%) were obtained for the orthogonal bar slit pattern (slit width=0.75 /spl mu/m) with surface planarization.

Application of bi-directional thin-film micro wire array to RF integrated spiral inductors

Vertically and horizontally aligned micro wire arrays with the magnetic hard axis perpendicular to the length of the wire are micro-fabricated from zero-magnetostrictive CoNbZr film. Annealing produced a 180-degree domain pattern, small coercive force and good permeability. Using the micro wire array with line/space=9 /spl mu/m/2 /spl mu/m, an RF integrated inductor exhibited L=7.5 nH(+11% of air cores), R=7.6 /spl Omega/ and Q=6.3 (almost same as the air cores).

Magnetic properties of Fe alloy/Permalloy multilayered films

Abstract Fe-Si/Permalloy and Fe-Ni/Permalloy multilayered films were prepared by a conventional rf sputtering method. A Permalloy interlayer is effective in obtaining high initial permeability and a good correlation between the permeability and the (110)/(211) X-ray diffraction intensity ratio was found. This result indicates that the crystal orientation of grains plays an important role in obtaining a high initial permeability. The permeability of the Fe-Si/Permalloy multilayered films decreases after annealing processes above 400°C because of the diffusion of Ni atoms into the Fe-Si alloy layer. To prevent the influence of Ni diffusion and also to improve the thermal stability, the thickness ratio of Fe-Si/Permalloy was found to be important.

Eddy currents and displacement currents in multi-layer soft magnetic films for recording heads

Eddy current loss has become a significant problem in the development of soft magnetic films as the signal frequency has become higher. In thick soft magnetic films, it has been proposed that layering of the film reduces the eddy current loss. However, there was a hypothesis that displacement current flows through the insulator such as a capacitor sandwiched by two metal films and that multi-layered films are not so efficient at a high frequency. By using a 3D-FEM (Finite Element Method). we found that the displacement current is smaller than the eddy current by a factor of lo6 for 0.5 pm thick insu1ator.l In this study the insulator thickness was changed from 0.05km to l p m and the effects of pin holes and the passage of eddy currents through metal on the edge of insulator was investigated precisely. The computation results was confirmed by using large scale models.

Effects of interlayers on the soft magnetic properties of Fe-Si multilayers

Abstract In order to realize low coercivity in Fe-9.0wt%Si-based multilayer films, the correlation between coercivity and the crystalline structure has been investigated. Crystalline orientation is an important factor for the low coercivity of Fe-Si-based multilayer films. Permalloy is found to be the most suitable interlayer for achieving low coercivity.

Thin Film Head for Perpendicular Magnetic Recording

Thin film heads for perpendicular recording were fabricated, with a main pole of Co-Zr-Nb and auxiliary pole of Permalloy, and their performances compared with those of unilateral bulk-type heads. When recording at 1.7 kFCI, the thin film heads yielded outputs twice as high as bulk heads at the same recording current. According to FEM analyses, this is because from 25 to 50 percent of the magnetic flux passing through the pole tip is linked with the coil, versus only about 15 percent for bulk heads. If the auxiliary pole thickness, auxiliary pole tip position and other factors are optimized, further improvements in sensitivity are possible.

Transition analysis of magnetic recording heads using FDTD

Transition waveforms of a magnetic recording head have been analyzed using finite difference time domain (FDTD). The distributed inductance and capacitance of the head effect the rising time of the magnetic fields in the recording process. FDTD electromagnetic analysis is easy to combine with SPICE circuit analysis. Using this combined program, a transition analysis of the recording process including a write amplifier has become possible.

Effects of pole tip configuration on side-cross-talk of thin film heads for VCR

The authors point out that the write fringing field and the cross-talk with the adjacent track of film heads depend on the rubbing surface configuration. The optimum rubbing surface configuration was designed by analyses using 3-D FEM and the reciprocity theorem, considering the easiness of the ion-milling process and the recording properties. Two types of heads were fabricated and their cross-talk properties were compared experimentally. The read/write cross-talks are reduced drastically by using the improved head configuration. The just off-track output value is less than -35 dB of the just on-track output. >

Mössbauer analyses of FeSiAl and FeSiAlN sputtered films

Abstract Microstructural variations with the annealing temperature for FeSiAl and FeSiAlN films were measured by CEMS (conversion electron Mossbauer microscopy). The ordering starts around 670 K and is completed around 900 K. After 923 K annealing, the D03 structure in the FeSiAl film is formed, the D03 structure and D03-like structure, where one D-site Si or Al is substituted by one Fe, is formed in the FeSiAlN film. The variation of the permeability agrees with the microstructural variation.