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Dive into the research topics where Hidemasa Kubota is active.

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Featured researches published by Hidemasa Kubota.


custom integrated circuits conference | 2005

Generalized method of the time-domain circuit simulation based on LIM with MNA formulation

Hidemasa Kubota; Yuichi Tanji; Takayuki Watanabe; Hideki Asai

In this paper, we show the generalized method of the time-domain circuit simulation based on LIM. First, the formulation of the circuit for LIM is modified and generalized. Furthermore, the modified simulation algorithm is suggested. As a result, our method is applicable to any structure of circuits. Some example circuits are simulated and the proposed method is compared with the conventional ones, in order to show the validity and efficiency of our method


design, automation, and test in europe | 2006

Large Scale RLC Circuit Analysis Using RLCG-MNA Formulation

Yuichi Tanji; Takayuki Watanabe; Hidemasa Kubota; Hideki Asai

A fast method for timing analysis of large scale RLC networks using the RLCG-MNA formulation, which provides good properties for fast matrix solvers, is presented. The proposed method is faster than INDUCTWISE and more general than the RLP algorithm, where INDUCTWISE and RLP algorithm are known as the state-of-art simulation methods. In the numerical example, good performances of the proposed method are illustrated compared with the previous works


asia and south pacific design automation conference | 2006

Parallel-distributed time-domain circuit simulation of power distribution networks with frequency-dependent parameters

Takayuki Watanabe; Yuichi Tanji; Hidemasa Kubota; Hideki Asai

In this paper, we focus on the verification of the PCB/package power integrity, which becomes very important for the design of state-of-art high speed digital circuits. The simulation of power distribution networks (PDNs) of the PCB/package, which can be modeled as a large number of RLC lumped components, is a time-consuming task for using the conventional circuit simulator, such as SPICE. For this problem, we propose a parallel-distributed time-domain circuit simulation algorithm based on LIM. Furthermore, an effective modeling of frequency-dependencies of the PDNs, such as skin effects and dielectric losses, to solve by LIM is proposed


IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences | 2007

Fast Transient Simulation of Power Distribution Networks Containing Dispersion Based on Parallel-Distributed Leapfrog Algorithm

Takayuki Watanabe; Yuichi Tanji; Hidemasa Kubota; Hideki Asai

This paper presents a fast transient simulation method for power distribution networks (PDNs) of the PCB/Package. Because these PDNs are modeled as large-scale linear circuits consisting of a large number of RLC elements, it takes large costs to solve by conventional circuit simulators, such as SPICE. Our simulation method is based on the leapfrog algorithm, and can solve RLC circuits of PDNs faster than SPICE. Actual PDNs have frequency-dependent dispersions such as the skin-effect of conductors and the dielectric loss. To model these dispersions, more number of RLC elements are required, and circuit structures of these dispersion models are hard to solve by using the leapfrog algorithm. This paper shows that the circuit structures of dispersion models can be converted to suitable structures for the leapfrog algorithm. Further, in order to reduce the simulation time, our proposed method exploits parallel computation techniques. Numerical results show that our proposed method using single processing element (PE) enables a speedup of 20--100 times and 10 times compared to HSPICE and INDUCTWISE with the same level of accuracy, respectively. In a large-scale example with frequency-dependent dispersions, our method achieves over 94% parallel efficiency with 5PEs.


electrical performance of electronic packaging | 2003

What-if analyses of multi-layer PWB embedded in the digital still camera with parallel-distributed FDTD-based simulator "BLESS"

Kenji Araki; Hidemasa Kubota; Takayuki Watanabe; Hideki Asai

This paper describes a full-wave EMI (electromagnetic interference) simulator BLESS (Board Layout Evaluation and Suggestion System) for the printed wiring board (PWB) design with the consideration of electromagnetic compatibility (EMC) and power/signal integrity. This simulator is based on the parallel-distributed finite-difference time-domain (FDTD) method, and works on a PC-cluster. The accuracy of analysis by BLESS is verified in comparison with s-parameter measurements. Using the simulator, the full-wave analysis of the multi-layer PWB in a commercial digital still camera is demonstrated. With the aid of what-if analysis results, PWB design can be verified and optimized with less number of trial productions.


electrical performance of electronic packaging | 2001

Analysis of power/ground planes by PCB simulator with model order reduction technique

Hidemasa Kubota; Atsushi Kamo; Talcam Watanabe; Hideki Asai

With the progress of integration of circuits and PCBs (printed circuit boards), novel techniques have been required for verification of signal integrity. Noise analysis of the power/ground planes is one of the most important issues. This paper describes a high-speed simulator for PCBs which contain interconnects with nonlinear terminations. This simulator is based on the ASSIST environmental tool constructed for development of the circuit simulators, and is combined with PRIMA (passive reduced-order interconnect macromodeling algorithm). In this simulator, an efficient implementation of PRIMA is considered with use of a voltage-controlled current source (VCCS) model. Finally, this simulator is applied to the analysis of power/ground planes of simple PCBs, and the validity is verified.


international symposium on quality electronic design | 2006

Quasi-One-Step Gauss-Jacobi Method for Large-Scale Interconnect Analysis via RLCG-MNA Formulation

Yuichi Tanji; Takayuki Watanabe; Hidemasa Kubota; Hideki Asai

One or 2-step Gauss-Jacobi method is efficiently incorporated to the large scale interconnect analysis. In order to make the Gauss-Jacobi method within 1 or 2 iterations during each time step, the interconnect network is formulated by the RLCG-MNA formulation. In the numerical example, it is illustrated that the one-step Gauss-Jacobi method is 1,035 times faster than Berkeley SPICE and several tens times faster than INDUCTWISE which is known as the recent fast simulation method. Further, we show that the 2-step Gauss-Jacobi method is rational from efficiency and accuracy points of views


international symposium on circuits and systems | 2005

Passive approximation of tabulated frequency-data by Fourier expansion method

Yuichi Tanji; Hidemasa Kubota

The passive approximation of tabulated frequency-data for modeling package, PCB, and integrated circuits is presented. The macromodels in the Laplace-domain are directly obtained by the Fourier series approximation of the frequency-data and are represented using a Laguerre basis. The rigorous proof of passivity preservation associated with the proposed models is provided.


design, automation, and test in europe | 2004

Hybrid reduction technique for efficient simulation of linear/nonlinear mixed circuits

Takashi Mine; Hidemasa Kubota; Atsushi Kamo; Takayuki Watanabe; Hideki Asai

In this paper, we propose a new method which makes transient simulation faster for the circuit including both nonlinear and linear elements. First, the method for generating the projection matrix with krylov-subspace technique is described. The order of the circuit equation is reduced by congruence transformation with the projection matrix. Next, we suggest a method which can calculate the reduced Jacobian matrix directly in the each Newton-Raphson iteration. Since this technique does not need to calculate the original size of Jacobian matrix, the calculation cost is reduced drastically. Therefore, efficient circuit simulation can be achieved. Finally, our method is applied to some example circuits: and the validity of the nonlinear circuit reduction technique is verified.


IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences | 2006

An Enhanced Time-Domain Circuit Simulation Technique Based on LIM

Hidemasa Kubota; Yuichi Tanji; Takayuki Watanabe; Hideki Asai

In this paper, we show the generalized method of the time-domain circuit simulation based on LIM. Our method is applicable to any structure of circuits by combination with the SPICE-like method. In order to show the validity and efficiency of our method, an example circuit is simulated and the proposed method is compared with the conventional ones.

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