記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

<p>We propose a coupled-map-lattice complementary-metal-oxide-semiconductor very-large-scale-integration (CMOS VLSI) circuit based on the threshold-coupled map (TCM) that has been proposed previously as a unidirectional connected network model exhibiting different spatiotemporal patterns according to its underlying nonlinear map and update scheme. We introduce mutual connections and arbitrarily valued connection weights into the TCM to realize cellular automata. In this study, we design, fabricate, and evaluate a CMOS integrated circuit with which to implement this extended TCM (ETCM). The ETCM is a universal Turing machine as confirmed in circuit experiments using the fabricated circuit, which can achieve Rule110 of a one-dimensional cellular automaton.</p>

DOI： 10.1587/nolta.9.268

CiNii Article

その他リンク： https://ci.nii.ac.jp/naid/130006602774

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）

記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

CiNii Article

その他リンク： https://ci.nii.ac.jp/naid/110009996023

担当区分：筆頭著者   記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

CiNii Article

その他リンク： https://ci.nii.ac.jp/naid/110009996024

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

In order to develop large-scale nonlinear dynamical systems using CMOS integrated circuits, we propose a core circuit for coupled map lattice (CML) models. The characteristics of the core circuits in the lattice on a chip are not generally equal, which is caused by CMOS device mismatches, including parasitic capacitance and wiring resistance. The proposed circuit solves this problem; it compensates for a DC offset voltage variation by holding it at a capacitor, and also for current variation by adjusting the bias voltage of a current source automatically so as to bring the current close to a target value. The proposed core circuit has been designed and fabricated using TSMC 0.25 µm CMOS technology. The measurement results using the fabricated circuit have shown that the bit precision is more than 8 bits, even if there is a DC offset voltage of 100 mV or a bias-voltage change of 100 mV in a switched current source.

その他リンク： https://ci.nii.ac.jp/naid/130005102329

記述言語：日本語   掲載種別：研究論文（研究会，シンポジウム資料等）

スパイク列のフィルタとして動作するスパイキングカオス振動子モデルを実行するCMOS回路を提案する.このモデルは一定角周波数で振動する位相振動子で,所定の位相になったタイミングでスパイクパルスを出力するとともに,スパイク入力のタイミングで位相状態を所定の非線形関数にしたがって変換する.このモデルは,入力スパイクの周波数が分岐パラメータになっており,これを変えることでスパイク列を出力しない場合も含め,様々なスパイク列を出力することができる.特定の周波数の入力スパイク列に対してスパイクを出力しないなどの特性は,スパイク列フィルタとして機能することを意味する.このモデルを実行する提案回路は定電流源で充電するキャパシタに蓄積される電荷量により位相状態値を表現し,CMOSトランジスタの非線形特性を利用して非線形変換を実現する.提案回路を標準CMOS集積回路技術により設計・試作し,スパイク列フィルタとしての特性を試作回路の測定により評価し,動作を確認した結果を示す.

CiNii Article

その他リンク： https://ci.nii.ac.jp/naid/110010002094

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

In order to develop large-scale nonlinear dynamical systems using CMOS integrated circuits, we propose a core circuit for coupled map lattice (CML) models. The characteristics of the core circuits in the lattice on a chip are not generally equal, which is caused by CMOS device mismatches, including parasitic capacitance and wiring resistance. The proposed circuit solves this problem; it compensates for a DC offset voltage variation by holding it at a capacitor, and also for current variation by adjusting the bias voltage of a current source automatically so as to bring the current close to a target value. The proposed core circuit has been designed and fabricated using TSMC 0.25 &micro;m CMOS technology. The measurement results using the fabricated circuit have shown that the bit precision is more than 8 bits, even if there is a DC offset voltage of 100 mV or a bias-voltage change of 100 mV in a switched current source.

DOI： 10.1587/nolta.6.570

CiNii Article

その他リンク： https://ci.nii.ac.jp/naid/130005102329

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

e experimentally study strange nonchaotic attractors (SNAs) and chaotic attractors by using a nonlinear integrated circuit driven by a quasiperiodic input signal. An SNA is a geometrically strange attractor for which typical orbits have nonpositive Lyapunov exponents. It is a difficult problem to distinguish between SNAs and chaotic attractors experimentally. If a system has an SNA as a unique attractor, the system produces an identical response to a repeated quasiperiodic signal, regardless of the initial conditions, after a certain transient time. Such reproducibility of response outputs is called consistency. On the other hand, if the attractor is chaotic, the consistency is low owing to the sensitive dependence on initial conditions. In this paper, we analyze the experimental data for distinguishing between SNAs and chaotic attractors on the basis of the consistency.
Strange nonchaotic attractors (SNAs) often appear in dynamical systems driven by a quasiperiodic signal. An SNA is a geometrically strange attractor for which typical orbits have nonpositive Lyapunov exponents. In fact, typical orbits are insensitive to initial conditions under a common quasiperiodic signal. Owing to their characteristics reminiscent of both quasiperiodic order and chaos, SNAs have attracted the attention of researchers from both theoretical and experimental perspectives. Conventionally, the information dimension is often employed to distinguish between SNAs and chaotic attractors in experiments. However, using the information dimension for the experimental distinction between these types of attractors is difficult as the estimation of the information dimension is highly sensitive to noise, and requires rather long time series. Recently, Ngamga et al.1 proposed a method for distinguishing between SNAs and chaotic attractors, which utilizes the consistency property of SNAs. Consistency here means that a nonlinear system shows the same response to the same input signal after some transient time, regardless of the initial conditions. In the method proposed by Ngamga et al., the determinism for a cross-recurrence plot of two response time series to the same input signal is used as a consistency measure. However, to our knowledge, there is no research paper on using their cross-recurrence method to experimentally distinguish between SNAs and chaotic attractors. In this study, we evaluated the consistency of a system by using the zero-delay normalized cross-correlation and Ngamga et al.'s cross-recurrence methods. By combining spectrum analysis and evaluation of consistency, we showed that SNAs and chaotic attractors can be distinguished more precisely as compared to conventional methods.

DOI： 10.1063/1.4804181

その他リンク： https://aip.scitation.org/doi/10.1063/1.4804181

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）

本研究では, CMOS集積回路による大規模結合非線形ダイナミカルシステム実現のために,素子ばらつきに頑健なしきい値結合アレイ回路を提案する.我々はすでに,任意の非線形ダイナミカルシステムの実現法として,外部から与えられる非線形電圧波形をパルス幅/位相変調(PWM/PPM)信号によりキャパシタにサンプリングし,任意の非線形変換を行う電圧サンプリング方式回路と,同じく非線形電流波形をPPM信号でキャパシタにサンプリングする電流サンプリンク方式回路を提案してきた.両サンプリング方式にはそれぞれ,原理的にCMOS回路に不可避な構成素子のパラメータばらつきに頑健てあること,および結合状態の積和計算がノード結線で容易に実現できることという長所がある.これら二つの長所は大規模結合系を実装する上で非常に重要である.そこで本研究ではこれら2っの長所を生かした回路構成を採用し,大規模結合CMOS回路で問題となるアナログバッファ回路のシフト電圧ばらつきに頑健な回路を提案する.さらに,提案回路が電圧シフトに頑健であることをSPICEシミュレーションにより示す.

CiNii Article

その他リンク： https://ci.nii.ac.jp/naid/110009728129

記述言語：英語   掲載種別：研究論文（学術雑誌）

Torus-doubling bifurcations typically occur only a finite number of times. It has been assumed that torus-doubling bifurcations in quasiperiodically forced systems are interrupted by the appearance of strange nonchaotic attractors (SNAs). In the present Letter, we study a quasiperiodically forced noninvertible map and report the occurrence of a torus-doubling process via SNAs. The mechanism of this process is numerically clarified. Furthermore, this process is experimentally demonstrated in a switched-capacitor integrated circuit.