Masato Ogata

Graph-theoretical approach to 2-switch DC-DC converters

SUMMARY This paper presents a graph-theoretic approach to analyse and synthesize switch mode DC–DC converters. The result is based on the state-space averaging equation and the fundamental graph theory. Hence our proposed method is applied to various kinds of DC–DC converters with two switches and topological conditions for two-switch DC–DC converters are obtained systematically. Copyright ? 2005 John Wiley & Sons, Ltd.

Topological criteria for switched mode DC-DC converters

In this paper we give a systematic analysis method for a class of switched mode DC-DC converters based on the graph theory and give very simple topological criteria for a circuit with 2 switches to work as DC-DC converter, in particular, buck, booster, and buck/booster converters. The results are illustrated with some examples.

Simple RC models of distributed RC lines in consideration with the delay time

Two simple lumped RC circuits are presented to model a single distributed RC line by very simple passive RC two-port network. These circuits give very accurate results for the 50% propagation delay of the RC distributed lines terminated with arbitrary load impedances. We first show that the step responses for the open circuited voltage transfer function, short circuited transfer admittance function, and the short circuit current transfer function which can be approximated accurately by functions of degree one or two as far as we concern with the delay characteristics.

Graph-theoretic approach to the design of four-switch DC-DC converters

This paper presents a graph-theoretic approach to analyze and synthesize DC-DC converters with four switches. The results are based on the state-space averaging equation and the fundamental graph theory. The proposed method can provide whole families of converters with four switches systematically.

Analysis of DC-DC converters containing a transformer

This paper gives rigorous analysis of a kind of switching converters containing a transformer and shows that some graph-theoretic interpretation for them to work as DC-DC converters is possible

Simultaneous realization of Z/sub 21//Z/sub 11/ and Y/sub 21/ of an RC two-port

In this paper we give the necessary and sufficient conditions for the prescribed functions z/sub 21//z/sub 11/ and y/sub 21/ to be realizable simultaneously as an RC two-port.

On the Potential Instability of an RC Active Filter with Op-amps

When we design a prescribed transfer function T(s) = Q(s)/P(s), the designed circuit surely realize the above T(s) if op-amps are ideal. However due to the above-mentioned frequency characteristics of op-amps there arise higher order terms in the denominator of the transfer function.These parasitic terms have positive or negative sign. Thus in the worst case we cannot cancel a negative term by positive terms because these coefficients are not predictable a priori.When we design the circuit, it is preferable to avoid the circuit which may be potentially unstable. It is therefore preferable to give some criteria for a class of circuit to be potentially unstable.This paper give some topological criteria for an op-amp circuit to be potentially unstable. The criteria is graph-theoretic, but the conclusion is very familiar to active circuit designer.