Shiro Yoshida

Novel decoupling circuit enabling notable electromagnetic noise suppression and high-density packaging in a digital printed circuit board

This paper describes a novel decoupling circuit comprising magnetic materials and built-in choking coils which makes it possible to significantly suppress noise in a digital printed circuit board (PCB). It is well known that the common-mode current existing in the cables and chassis of digital equipment causes major radio frequency radiation from equipment. We found that the common-mode current in the digital PCB could be substantially reduced by enhancing the decoupling circuit of the DC supply line near the LSIs in the PCB. Experiments confirmed that use of the enhanced circuit greatly reduces the amount of radio frequency radiation emitted from digital equipment under normal circumstances.

SDI (strategic dual image) solution of PCB (printed circuit board) containing magnetic material

One way to control electromagnetic interference (EMI) generated on a printed circuit board (PCB) operating at high frequency is to cover the power layer by a magnetic thin film. The device modeling makes it possible to analyze electromagnetic features and then to optimize the device performances. This paper presents the finite element modeling of a 2D axisymmetric, magnetodynamic, unbounded problem composed of a PCB containing a Mn-Zn ferrite thin film. Hysteresis is taken into account in the computation. The final solution is obtained by using the strategic dual image method (SDI). The results show especially the good performances of this device configuration at high frequency, up to 1 GHz.

Novel decoupling circuit comprising magnetic materials and built-in choking coils

This paper describes a novel decoupling circuit comprising magnetic materials and built-in choking coils which makes it possible to significantly suppress noise and improve noise immunity in a digital printed circuit board (PCB).

Current distribution analysis on printed circuit board

This paper proposes a methodology for identifying a major electromagnetic radiation noise source from mother boards used in computers. The key idea is based on a combination of the discretized Helmholtz theorem and minimum norm strategy. Application of our methodology clarifies that the rotational current distributions work as one of the loop antennas. Thus, we have succeeded in identifying a major noise cause of the mother boards.

Rotational and divergent components identification of vector fields by the minimum norm method

Publisher Summary This paper proposes a post-processing method, which classifies the source component vectors to be identified. The key idea is to classify the rotational and divergent vector fields. By means of the Helmholtz theorem, any vector can be represented as the summation of rotational and divergent vector fields. To evaluate the rotational and divergent fields, it is essential to solve an inverse problem whose solution is composed of the scalar and vector potentials. The solution methodology to this inverse problem is the minimum norm method. A rotational vector field can be obtained by taking a rotation of the vector potentials. Also, a divergent vector field can be obtained by taking a gradient of scalar potentials. First, an inverse approach for identifying both of unknown scalar and vector potentials out of known two-dimensional current fields is proposed. Second, the numerical simulations are carried out to check up the validity of our method. Finally, the method is applied to the practical problems, which are concerning the searching for eddy current and source current from the locally measured magnetic fields.