Journal of the Institute of Electronics Engineers of Korea SD (대한전자공학회논문지SD)

The Institute of Electronics and Information Engineers (대한전자공학회)
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An Energy Efficient $V_{pp}$ Generator using a Variable Pumping Clock Frequency for Mobile DRAM

가변 펌핑 클록 주파수를 이용한 모바일 D램용 고효율 승압 전압 발생기

  • 김규영 (고려대학교 전기컴퓨터공학과) ;
  • 이두찬 (고려대학교 나노반도체공학과) ;
  • 박종선 (고려대학교 전기전자전파 공학부) ;
  • 김수원 (고려대학교 전기전자전파공학부)
  • Received : 2009.11.20
  • Accepted : 2010.05.19
  • Published : 2010.06.25
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Abstract

A energy efficient $V_{pp}$ generator using a variable pumping frequency for mobile DRAM is presented in this paper. The proposed $V_{pp}$ generator exploits 3 stages of a cross-coupled charge pump for energy efficiency. Instead of using a fixed pumping frequency in the conventional $V_{pp}$ generator, our proposed $V_{pp}$ generator adopts a voltage-controlled oscillator and uses variable frequencies to reduce the ramp-up time. As a result, our $V_{pp}$ generator generates 3.0 V output voltage with 24.0-${\mu}s$ ramp-up time at 2 mA current load and 1 nF capacitor load with 1.2 V supply voltage. Experimental results show that the proposed $V_{pp}$ generator consumes around 26% less energy (1573 nJ $\rightarrow$ 1162 nJ) and reduces 29% less ramp-up time (33.7-${\mu}s$ $\rightarrow$ 24.0-${\mu}s$) compared to the conventional approach.

본 논문에서는 가변 펌핑 클록 주파수를 이용한 모바일 D랩용 고효율 승압 전압 발생기를 제안한다. 제안된 승압 전압 발생기는 효율을 높이기 위해서 3단 Cross-coupled 점하 펌프를 사용하였으며, 또한 최종 출력 전압의 승압 시간을 줄이기 위해 기존의 승압 전압 발생기에서 사용되는 고정된 펌핑 클록 주파수 대신 전압 제어 발생기를 사용하여 펌핑 클록 주파수을 가변하였다. 따라서 제안된 승압 전압 발생기는 1.2 V 전원 전압, 최대 2 mA의 부하 전류, 1 nF의 부하 캐퍼시터 조건에서 24.0-${\mu}s$안에 3.0 V의 최종 출력 전압을 승압할 수 있다. 실험 결과 제안된 승압 전압 발생기는 에너지 소비를 26% (1573 nJ $\rightarrow$ 1162 nJ), 승압 시간을 29% (33.7-${\mu}s$ $\rightarrow$ 24.0-${\mu}s$) 감소시켰다. 따라서 제안된 승압 전압 발생기를 사용함으로써, 높은 에너지 효율과 빠른 승압을 동시에 구현할 수 있다.

Keywords

References

  1. C. G. Hwang, "New paradigms in the silicon industry," in IEDM Tech. Dig., 2006, pp. 1-8.
  2. K. Itoh, et al., "Memory at VLSI circuits symposium," IEEE J. Solid-State Circuits, vol. 43, no. 4, pp. 762-768, Apr. 2008. https://doi.org/10.1109/JSSC.2008.917527
  3. S. -I. Cho, et al., "Two-phase boosted voltage generator for low-voltage DRAMS," IEEE J. Solid-State Circuits, vol. 38, no. 10, pp. 1726-1729, Oct. 2003. https://doi.org/10.1109/JSSC.2003.817592
  4. C. C. Wang and J. C. Wu, "Efficiency improvement in charge-pump circuits," IEEE J. Solid-State Circuits, vol. 32, pp. 852-860, June 1997. https://doi.org/10.1109/4.585287
  5. J. F. Dickson, "On chip high voltage generation in NMOS integrated circuits using an improved voltage multiplier technique," IEEE J. Solid-State Circuits, vol. 11, no. 3, pp. 374-378, Jun. 1976. https://doi.org/10.1109/JSSC.1976.1050739
  6. J. -T. Wu and K. -L. Chang, "MOS charge pump for low-voltage operation," IEEE J. Solid-State Circuits, vol. 33, no. 4, pp. 592-597, Apr. 1998. https://doi.org/10.1109/4.663564
  7. R. Pelliconi, et al., "Power efficient charge pump in deep submicron standard CMOS technology," IEEE J. Solid-State Circuits, vol. 38, no. 6, pp. 1068-1071, Jun. 2003. https://doi.org/10.1109/JSSC.2003.811991
  8. M. -D. Ker, S. -L. Chen and C. -S. Tsai, "Design of charge pump circuit with consideration of gate-oxide reliability in low-voltage CMOS processes," IEEE J. Solid-State Circuits, vol. 41, no. 5, pp. 1100-1107, May 2006. https://doi.org/10.1109/JSSC.2006.872704
  9. T. Tanzawa and T. Tanaka, "A dynamic analysis of the Dickson charge pump circuit," IEEE J. Solid-State Circuits, vol. 32, no. 8, pp. 1231-1240, Aug. 1997. https://doi.org/10.1109/4.604079
  10. G. -H. Lim, et al., "Charge pump design for TFT-LCD driver IC using stack-MIM capacitor," IEICE Trans. Electron., vol. E91-C, no. 6, pp. 928-935, Jun. 2008. https://doi.org/10.1093/ietele/e91-c.6.928
  11. J. -Y. Lee, et al., "A regulated charge pump with small ripple voltage and fast start-up," IEEE J. Solid-State Circuits, vol. 41, no. 2, pp. 425-432, Feb. 2006. https://doi.org/10.1109/JSSC.2005.862340
  12. J. M. Rabaey, A. Chandrakasan and B. Nikolic, Digital Integrated Circuits, 2nd edition, Prentice-Hall, 2005.