Hirokazu Tohya

Resonance stub effect in a transition from a through via hole to a stripline in multilayer PCBs

We present results of study of the resonance stub effect occurring in a transition from a through via hole to a stripline in a multilayer printed circuit board (PCB). This effect for via structures including ground vias is estimated by numerical simulations and measurements in the frequency band up to 20 GHz. Ways to alleviate problems in the design of interconnections embedded in multilayer PCBs due to the resonance stub effect and possible applications of the effect in microwave filtering are traced.

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.

SPICE simulation of power supply current from LSI on PCB with a behavioral model

This paper proposes a new behavioral model of an LSI to simulate current in the power supply line of a PCB. The models impedance changes with time, thus ensuring simulation accuracy. The new model makes it possible to easily simulate the current in a PCB power supply line. Good agreement is obtained between simulated values and measured in experiments.

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.

Low impedance line structure component (LILC) for power distribution system in the high-performance digital circuit

This paper describes an improved power distribution system (PDS) in high performance digital circuits, including the LSI package and the SoC (system on a chip). The novel technology of LILC (low impedance line structure component) suitable for PDS is introduced. The limitation of the traditional capacitor technology in the PDS is also shown.

A methodology to simulate the electromagnetic behavior of printed circuit boards including magnetic materials

This paper presents a methodology to simulate the high frequency electromagnetic behavior of Printed Circuit Boards (PCBs) including magnetic materials. The modeling accounts for displacement and eddy currents. The magnetic hysteresis is efficiently represented by a complex permeability model. The problem is considered as unbounded, bi-dimensional, axisymmetric. A combined Finite Element (FE) and Strategic Dual Image (SDI) method is used to compute the electric and magnetic fields. A comparative study of two PCBs examples, one including a MnZn ferrite film, is investigated and some features as the magnetic flux distributions and the derived equivalent electric circuits are discussed.

Characterisation of printed circuit boards including magnetic film using finite element analysis

A method to evaluate the characteristics of printed circuit boards containing magnetic films is proposed. By means of electromagnetic field distribution computed from a combined finite element method and strategic dual image method, the equivalent circuit parameters R, L, C are determined. The employed methodology which accounts for eddy currents, displacement currents and hysteresis is detailed in the case of 2D axisymmetric problems. Then two simple PCB configurations are investigated. The results clearly show that the NiZn ferrite composite material included in one PCB reduces EMI efficiently.

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.