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Current Mode, Voltage Mode, or Free Mode? A Few Sage Suggestions

  • Barrie Gilbert
Article

Abstract

Many claims have been made about the benefits of a current-mode (CM) approach to IC design. The term is used to draw attention to some kind of special dependence on currents as signals, often without a clear orientation to the broader field, referring instead to recent CM papers. Its use suggests a significant and valuable distinction over “conventional” solutions, perhaps in the hope that this perspective, with an element of novelty at the cell level, will influence circuit design in the stringent context of IC production. This paper asks: What factors unambiguously define a current-mode circuit, and formally differentiate it from standard realizations of some function? Can one point to any compelling, and in the most favorable cases unique, advantages? Are these cells clearly of general value, capable of widespread utility? These issues are examined from the critical viewpoint that no circuits carry the entire functional burden by the exclusive use of either currents or voltages, and very few fully exploit the specific, but narrow, benefits of CM concepts. Real-world product development invariably demands the vigilant and full embrace of what might be called the Free Mode perspective, but merely as a mnemonic, not a classification.

current mode analog design techniques 

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References

  1. 1.
    J. Huijsing, R. van de Plassche, W. Sansen (Eds.), Analog circuit design: Low-noise, low-power, low-voltage; Mixed-Mode Design wit Cad Tools; Voltage, Current and Time References. Kluwer, 1996, pp. 269–352.Google Scholar
  2. 2.
    A.F. Arbel, “Comparison between the noise performance of current-mode and voltage-mode amplifiers.” Analog Integrated Circuits and Signal Processing Journal, vol. 7, no. 3, pp. 221–242, 1995.Google Scholar
  3. 3.
    GCM in Electronics Letters.Google Scholar
  4. 4.
    C. Toumazou, F.J. Lidgey, D.G. Haigh (Eds.), “Analogue IC design: The current-mode approach.” IEE Circuits and Systems Series 2, Perigrinus Press, 1990; Chapter 6, B. Gilbert, “Current Mirrors”, Sec. 6.5.5.Google Scholar
  5. 5.
    B. Gilbert, “Anewwideband amplifier technique.” IEEE Journal of Solid State Circuits, vol. SC-3, no. 4, pp. 353–365, 1968.Google Scholar
  6. 6.
    B. Gilbert, “The multi-tanh principle: A tutorial overview.” IEEE Journal of Solid State Circuits, vol. 33, no. 1, pp. 2–17, 1998.Google Scholar
  7. 7.
    B. Gilbert, “Aprecise four-quadrant multiplier with subnanosecond response.” IEEE Journal of Solid State Circuits, vol. SC-3, no. 4, pp. 365–373, 1968.Google Scholar
  8. 8.
    Later TL cell.Google Scholar
  9. 9.
    Unavailable at time of publication.Google Scholar
  10. 10.
    Seevinck thesis.Google Scholar
  11. 11.
    B. Gilbert, “Translinear circuits: A proposed classification.” IEE Electronics Letters, vol. 11, no. 1, pp. 14–16, 1975.Google Scholar
  12. 12.
    Many papers using MOS in weak inversion.Google Scholar
  13. 13.
    A.G. Andreou and K.A. Boahen, “Translinear cicruits in sub-threshold MOS.” Analog Integrated Circuits and Signal Processing Journal, vol. 9, no. 2, pp. 141–166, 1996.Google Scholar
  14. 14.
    B.A. Minch, C. Dioro, P. Hasler, and C.A. Mead, “Translinear circuits using subthreshold floating-gate MOS transistors.” Analog Integrated Circuits and Signal Processing Journal, vol. 9, no. 2, pp. 167–180, 1996.Google Scholar
  15. 15.
    J. Mulder, “Dynamic translinear circuits: An overview.” Analog Integrated Circuits and Signal Processing Journal, vol. 22, no. 2, pp. 111–126, 2000.Google Scholar
  16. 16.
    D.R. Frey, “Log-domain filtering: An approach to current-mode filtering.” IEE Proceedings, vol. 140, no. 6, pp. 406–415, 1993.Google Scholar
  17. 17.
    M. Punzenberg and C. Enz, “A compact low-power BiCMOS log-domain filter.” IEEE Journal of Solid State Circuits, vol. 33, no. 7, pp. 1123–1128, 1998.Google Scholar
  18. 18.
    B. Gilbert, “Translinear circuits: An historical review.” Analog Integrated Circuits and Signal Processing Journal, vol. 9, no. 2, pp. 95–118, 1996.Google Scholar
  19. 19.
    R.J. Weigerink, “Computer-aided analysis and design of MOS translinear circuits operating in strong inversion.” Analog Integrated Circuits and Signal Processing Journal, vol. 9, no. 2, pp. 181–188, 1996.Google Scholar
  20. 20.
    L. Magram and A.F Arbel, “Application of complementary techniques to a bipolar translinear gain cell and a translinear CCII+.” Analog Integrated Circuits and Signal Processing Journal, vol. 9, no. 2, p. 119, 1996.Google Scholar
  21. 21.
    J. Ahn and N. Fujii, “Current-mode continuous-time filters using complementary current-mirror pairs.” Analog Integrated Circuits and Signal Processing Journal, vol. 11, no. 2, pp. 109–118, 1996.Google Scholar

Copyright information

© Kluwer Academic Publishers 2004

Authors and Affiliations

  • Barrie Gilbert
    • 1
  1. 1.Analog Devices Inc.BeavertonUSA

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