近年の環境保全とエネルギー消費への意識の高まりから、これまで以上に低消費電力かつインテリジェントな情報処理を行なうコンピュータの実現が期待されている。半導体プロセスの微細化はLSIの低消費電力化、高集積化へつながるため、微細化を進めることがその実現への近道といえる。事実、LSIの微細化により、モバイル情報機器はバッテリ駆動時間を犠牲にせずより高速のプロセッサを搭載するようになっている。一方で、半導体プロセスルールがナノスケールになったことで、素子バラツキや環境雑音が回路特性に大きな影響を及ぼすようになった。これまでゆらぎや雑音は半導体プロセスの面や半導体プロセスの後処理などの面から多大なコストをかけて排除されてきたが、微細化と低電圧化によりさらに厳しい状況になっている。微細化の極端な例として、単電子トランジスタ(Single Electron Transistor, SET)と呼ばれる次世代情報処理デバイスをとりあげる。これは電子一つで制御できるトランジスタであり、現行のトランジスタと比較して格段に低い消費電力で動作する。しかし熱ゆらぎや微細な電気的な変化によって電子トンネリングが起きてしまうため、低温(数K)かつ非常に精度の高い製造技術が必要となる。
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Oya T., Schmid A., Asai T., and Utagawa A., "Stochastic resonance in a balanced pair of single-electron boxes," Fluctuation and Noise Letters, vol. 10, no. 3, pp. 267-275 (2011).
Utagawa A., Asai T., and Amemiya Y., "High-fidelity pulse density modulation in neuromorphic electric circuits utilizing natural heterogeneity," Nonlinear Theory and Its Applications, vol. 2, no. 2, pp. 218-225 (2011).
Utagawa A., Asai T., Hirose T., and Amemiya Y., "Noise shaping pulse-density modulation in inhibitory neural networks with subthreshold neuron circuits," Brain-Inspired IT III, Natsume K., Hanazawa A., and Miki T., Eds, International Congress Series, vol. 1301, pp. 71-74, Elsevier, Netherlands (2007).
招待講演/セミナー
宇田川 玲, "次世代ナノエレクトロニクスに向けたゆらぎの役割と応用〜双安定系を例にとって〜," 第15回情報バイオトロニクス研究会, Sapporo, Japan (Jun. 11, 2010).
Utagawa A., Asai T., and Amemiya Y., "Stochastic resonance in a simple electric circuit having a double-well potential ---Circuit experiments with a single operational amplifier---," Proceedings of 2010 International Symposium on Nonlinear Theory and its Applications, pp. 55-59, Krakow, Poland (Sep. 5-8, 2010).
Utagawa A., Asai T., and Amemiya Y., "Stochastic resonance in neuromorphic semiconductor devices having a double-well potential," Proceedings of the 14th International Conference on Cognitive and Neural Systems, p. 86, Boston, U.S.A. (May 19-22, 2010).
Utagawa A., Asai T., and Amemiya Y., "A noise-driven neuromorphic pulse-density modulator: experimental results with discrete MOS devices," Proceedings of the 2009 International Symposium on Nonlinear Theory and its Applications, pp. 206-209, Sapporo, Japan (Oct. 18-21, 2009).
Utagawa A., Asai T., and Amemiya Y., "Noise-induced phase synchronization among analogue oscillator circuits: Experimental results with discrete MOS devices," Proceedings of the 17th International Workshop on Nonlinear Dynamics of Electronic Systems, pp. 110-113, Rapperswil, Switzerland (Jun. 21-24, 2009).
Utagawa A., Asai T., and Amemiya Y., "High-fidelity neuromorphic pulse-sendity modulator based on a model of vestibulo-ocular reflex," Proceedings of the 13th International Conference on Cognitive and Neural Systems, p. 140, Boston, U.S.A. (May 27-30, 2009).
Utagawa A., Asai T., Sahashi T., and Amemiya Y., "Stochastic resonance in retinomorphic neural networks with nonidentical photoreceptors and noisy McCulloch-Pitts neurons," Proceedings of the 2008 International Symposium on Nonlinear Theory and its Applications, pp. 124-127, Budapest, Republic of Hungary (Sep. 7-10, 2008).
Utagawa A., Asai T., Hirose T., and Amemiya Y., "Noise-induced synchronization among sub-RF CMOS neural oscillators for skew-free clock distribution," Proceedings of the 2007 International Symposium on Nonlinear Theory and its Applications, pp. 329-332, Vancouver, Canada (Sep. 16-19, 2007).
Utagawa A., Asai T., Hirose T., and Amemiya Y., "Noise shaping pulse-density modulation in inhibitory neural networks with noise-sensitive subthreshold neuron circuits," Abstracts of the 3rd International Conference of Brain-inspired Information Technology, p. 42, Kitakyushu, Japan (Sep. 27-29, 2006).
Utagawa A., Asai T., Hirose T., and Amemiya Y., "A neuromorphic LSI performing noise-shaping pulse-density modulation with ultralow-power subthreshold neuron circuits," Proceedings of the 10th International Conference on Cognitive and Neural Systems, p. 53, Boston, U.S.A. (May 17-20, 2006).