병렬 연결된 다수의 디지털 구동기를 이용한 High-Q 디지털-아날로그 가변 축전기

High-Q Micromechanical Digital-to-Analog Variable Capacitors Using Parallel Digital Actuator Array

  • 한원 (KAIST 바이오및뇌공학과 디지털나노구동연구단) ;
  • 조영호 (KAIST 바이오및뇌공학과 및 기계공학과 디지털나노구동연구단)
  • 발행 : 2009.01.01

초록

We present a micromechanical digital-to-analog (DA) variable capacitor using a parallel digital actuator array, capable of accomplishing high-Q tuning. The present DA variable capacitor uses a parallel interconnection of digital actuators, thus achieving a low resistive structure. Based on the criteria for capacitance range ($0.348{\sim}1.932$ pF) and the actuation voltage (25 V), the present parallel DA variable capacitor is estimated to have a quality factor 2.0 times higher than the previous serial-parallel DA variable capacitor. In the experimental study, the parallel DA variable capacitor changes the total capacitance from 2.268 to 3.973 pF (0.5 GHz), 2.384 to 4.197 pF (1.0 GHz), and 2.773 to 4.826 pF (2.5 GHz), thus achieving tuning ratios of 75.2%, 76.1%, and 74.0%, respectively. The capacitance precisions are measured to be $6.16{\pm}4.24$ fF (0.5 GHz), $7.42{\pm}5.48$ fF (1.0 GHz), and $9.56{\pm}5.63$ fF (2.5 GHz). The parallel DA variable capacitor shows the total resistance of $2.97{\pm}0.29\;{\Omega}$ (0.5 GHz), $3.01{\pm}0.42\;{\Omega}$ (1.0 GHz), and $4.32{\pm}0.66\;{\Omega}$ (2.5 GHz), resulting in high quality factors which are measured to be $33.7{\pm}7.8$ (0.5 GHz), $18.5{\pm}4.9$ (1.0 GHz), and $4.3{\pm}1.4$ (2.5 GHz) for large capacitance values ($2.268{\sim}4.826$ pF). We experimentally verify the high-Q tuning capability of the present parallel DA variable capacitor, while achieving high-precision capacitance adjustments.

키워드

참고문헌

  1. J. J. Yao, 'RF MEMS from a device perspective,' J. Micromech Microeng., vol. 10, pp. 9-38. 2000 https://doi.org/10.1088/0960-1317/10/4/201
  2. C. L. Goldsmith, A. Malczewski, J. J. Yao, S. Chen, J. Ehmke, and D. H. Hinzel, 'RF-MEMS variable capacitors for tunable filters,' Int. J. RF Microw. Comput. Adided Eng., vol. 9, pp. 362-374, 1999 https://doi.org/10.1002/(SICI)1099-047X(199907)9:4<362::AID-MMCE7>3.0.CO;2-H
  3. J. Brank, J. Yao, M. Eberly, A. Malczewski, K. Varian, and C. L. Goldsmith, 'RF MEMS-based tunable filters,' Int. J. RF Microw. Comput. Adided Eng., vol. 11, pp. 276-284, 2001 https://doi.org/10.1002/mmce.1036
  4. L. Dussopt and G. M. Reibeiz, 'An X-to Ku-band 3-bit digital MEMS varactor,' IEEE Microw. Wirel. Compon. Lett., vol. 13, pp. 361-363, 2003 https://doi.org/10.1109/LMWC.2003.817118
  5. K. Entesari and G. M. Rebeiz, 'A 12-18-GHz three-pole RF MEMS tunable filter,' IEEE Trans. Microw. Theory Tech, vol. 53, pp. 2566-2571, 2005 https://doi.org/10.1109/TMTT.2005.852761
  6. D. J. Young and B. E. Boser, 'A micromachined variable capacitor for monolithic low-noise VCOs,' in Proc. Solid State Sensor and Actuator Workshop, 1996, pp. 86-89
  7. A. Dec and K. Suyama, 'Micromachined varactor with wide tuning range,' Electron. Lett. vol. 33, pp. 922-944, 1997 https://doi.org/10.1049/el:19970628
  8. H. D. Nguyen, D. Hah, P. R. Patterson, R. Chao, W. Piyawattanametha, E. K Lau, and M. C. Wu, 'Angular vertical comb-driven tunable capacitor with high-tuning capabilities,' J. Microeletromech Syst., vol. 13, pp. 406-413, 2004 https://doi.org/10.1109/JMEMS.2004.828741
  9. Z. Feng, W. Zhang, B. Su, K.F. Harsh, K.C. Gupta, V. Bright, and Y.C. Lee, 'Design and modeling of RF MEMS tunable capacitor using electro-thermal actuators,' Tech Digest IEEE MTT-S Int. Microwave Symp., 1999, pp. 1507-1510 https://doi.org/10.1109/MWSYM.1999.780240
  10. A. Dec and K. Suyama, 'Micromachined electro-mechanically tunable capacitors and their applications to RF IC's,' IEEE Trans. Microw. Theory Tech, vol. 46, pp. 2587-2596, 1998 https://doi.org/10.1109/22.739251
  11. R. Behn, H. Loebl, and K.-H. Preissinger, 'Electrical LC resonant circuit,' U. S. Patent 4095199, 1978
  12. H. Toshiyoshi, D. Kobayashi, M. Mita, G. Hashiguchi, H. Fujita, J. Endo, and Y. Wada, 'Microelectromechanical digital-to-analog converters of displacement for step motion actuators,' J. Microelectromech Syst., vol. 9, pp. 218-225, 2000 https://doi.org/10.1109/84.846702
  13. W. Han, W. C. Lee, and Y.-H. Cho, 'High-accuracy digital-to-analog actuators using the load springs compensating fabrication errors,' J. Microelectromech Syst., vol. 16, pp. 528-536, 2007 https://doi.org/10.1109/JMEMS.2007.896702
  14. W. Han and Y.-H. Cho, 'High-precision micromechanical tunable capacitors using parallel-interconnected digital actuators,' in Proc. Int. Conf, IEEE MEMS, 2007, pp. 815-818 https://doi.org/10.1109/MEMSYS.2007.4433177
  15. G. M. Rebeiz, RF MEMS Theory, Design, and Technology, NewJersey, John Wiley & Sons, 2003, pp. 328-330
  16. C. P. Yue and S. S. Wong, 'Physical modeling of spiral inductors on silicon,' IEEE Trans. Electron Devices. vol. 47, pp. 560-568, 2000 https://doi.org/10.1109/16.824729
  17. W. C. Lee, Y.-H. Jin and Y.-H. Cho, 'Nonlinearly modulated digital microactuators for nano-precision digital motion generation,' in Proc. Int. Conf. IEEE MEMS, 2002, pp.594-597 https://doi.org/10.1109/MEMSYS.2002.984341
  18. R. Zhou, H. Zhang, Y. Hao, and Y. Wang, 'Simulation of the Bosch process with a string-cell hybrid method,' J. Micromech Microeng., vol. 14, pp. 851-858, 2004 https://doi.org/10.1088/0960-1317/14/7/003
  19. R. L. Barwick Ill, P. A. Stupar, J. F. DeNatale. R. Anderson. and R. Erlandson, 'Variable MEMS capacitors implemented into RF filter systems.' IEEE Trans.Microwave Theory and Techniques. vol. 51, pp. 315-319, 2003 https://doi.org/10.1109/TMTT.2002.806519
  20. A. Fargas-MarQues. J. Casals-Terre, and A. M. Shkel, 'Resonant pull-in condition in parallel-plate electrostatic actuators,' J. Microelectromech Syst., vol. 16, pp. 1044-1053, 2007 https://doi.org/10.1109/JMEMS.2007.900893
  21. P. K. Petrov, N. M. Alford, and S. Gevorgyan, 'Techniques for microwave measurements of ferroelectric thin films and their associated error and limitations.' Meas. Sci. Technol. vol. 16, pp. 583-589, 2005 https://doi.org/10.1088/0957-0233/16/2/035