Digital Electronics: Fundamental Limits and Future Prospects

By Konstantin K. Likharev

Stony Brook University

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I will review some old and some recent work on the fundamental (and not so fundamental) limits imposed by physics of electron devices on their density and power consumption. In particular, I will discuss:

  • reversible computing, that allows one to beat the apparent Maxwell's-demon (E > kBTln2) and uncertainty-relation (E > /£n) "limits" for energy dissipation E per logic operation, and
  • quantum-mechanical effects that impose limits on shrinking of both field-effect and single-electron transistors.

I will argue that the impact of scaling limitations is grossly exacerbated by the economics of the current microcircuit fabrication paradigm. This problem may be overcome by transfer from the purely CMOS technology to hybrid "CMOL" integrated circuits. Such a circuit would combine an advanced (e.g., 45-nm) CMOS subsystem capped with two levels of mutually perpendicular nanowires. The nanowires are bridged with specially designed molecules that would self-assemble on them from solution. CMOL circuits may allow to combine advantages of their nanoscale components (e.g., reliability of CMOS circuits and miniscule footprint of molecular devices) and circumvent their drawbacks (e.g., low voltage gain of molecular devices), while keeping the fabrication facilities costs within reasonable limits. Possible architectures of CMOL circuits, and their speed vs. power consumption tradeoffs will be reviewed in brief.


Konstantin K. Likharev is a Distinguished Professor of Physics of the Stony Brook University (State University of New York). He received a Candidate (Ph.D.) degree in Physics from Lomonosov Moscow State University (Russia) in 1969, and the habilitation degree of Doctor of Sciences from the Higher Attestation Committee of the U.S.S.R. in 1979. From 1969 to 1988 Dr. Likharev was a Staff Scientist of Moscow State University, and from 1989 to 1991 the Head of the Laboratory of Cryoelectronics of that university. In 1991 he assumed the Professorship at Stony Brook. During his research career, Dr. Likharev worked in the fields of nonlinear classical dynamics, quantum dynamics and statistics, low-temperature solid-state physics and electronics, including nanoelectronics. He is an author/co-author of 2 monographs, 50 review papers and book chapters, 220+ original publications, and 18 patents. Prof. Likharev is an APS Fellow and IEEE member.

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  1. K. Likharev, "Classical and Quantum Limitations on Energy Consumption in Computation". Int. J. Theor. Phys. 21, No. 2/3, pp. 311-326 (1982).
  2. R. Landauer, "Dissipation and Noise Immunity in Computation and Communication", Nature 335, pp. 779-784 (1988).
  3. K. Likharev, "Electronics Below 10 nm". In: Nano and Giga Challenges in Microelectronics, ed. by J. Greer et al., Elsevier, Amsterdam, pp. 27-68 (2003). [Available on the Web at:]

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  • Konstantin K. Likharev (2004), "Digital Electronics: Fundamental Limits and Future Prospects,"

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