Optimized Design of Low Voltage High Current Ferrite Planar Inductor for 10 MHz On-chip Power Module

  • Bae, Seok (Department of Electrical and Computer Engineering, University of Alabama) ;
  • Hong, Yang-Ki (Department of Electrical and Computer Engineering, University of Alabama) ;
  • Lee, Jae-Jin (Department of Electrical and Computer Engineering, University of Alabama) ;
  • Abo, Gavin (Department of Electrical and Computer Engineering, University of Alabama) ;
  • Jalli, Jeevan (Department of Electrical and Computer Engineering, University of Alabama) ;
  • Lyle, Andrew (Department of Electrical and Computer Engineering, University of Alabama) ;
  • Han, Hong-Mei (Department of Electrical and Computer Engineering, University of Alabama) ;
  • Donohoe, Gregory W. (Department of Electrical and Computer Engineering, University of Idaho)
  • Published : 2008.06.30


In this paper, design parameters of high Q (> 50), high current inductor for on-chip power module were optimized by 4 Xs 3 Ys DOE (Design of Experiment). Coil spacing, coil thickness, ferrite thickness, and permeability were assigned to Xs, and inductance (L) and Q factor at 10 MHz, and resonance frequency ($f_r$) were determined Ys. Effects of each X on the Ys were demonstrated and explained using known inductor theory. Multiple response optimizations were accomplished by three derived regression equations on the Ys. As a result, L of 125 nH, Q factor of 197.5, and $f_r$ of 316.3 MHz were obtained with coil space of $127\;{\mu}m$, Cu thickness of $67.8\;{\mu}m$, ferrite thickness of $130.3\;{\mu}m$, and permeability 156.5. Loss tan ${\delta}=0$ was assumed for the estimation. Accordingly, Q factor of about 60 is expected at tan ${\delta}=0.02$.


  1. S. C. O. Matuna, T. O'Donnell, N. Wang, and K. Rinne, "Magnetics on Silicon: An Enabling Technology for Power Supply on Chip", IEEE Trans. on Power Electronics, 20 (3), 585 (2005)
  2. Enpirion, Inc. (2007). Products information of Enpirion, Inc. Available:
  3. P. Hazucha, S.-T. Moon, G. Schrom, F. Paillet, D. S. Gardner, S. Rajapandian, and T. Karnik, "High Voltage Tolerant Linear Regulator With Fast Digital Control for Biasing of Integrated DC-DC Converters", IEEE J. of Solid-State Circuits, 42, 66 (2007)
  4. P. Hazucha, G. Schrom, J.-H. Hahn, B. A. Bloechel, P. Hack, G. E. Dermer, S. Narendra, D. S. Gardner, T. Karnik, V. De, and S. Borkar, "A 233-MHz 80%-87% efficient four-phase DC-DC converter utilizing air-core inductors on package", IEEE J. of Solid-State Circuits, 40, 838 (2005)
  5. G. Schrom, P. Hazucha, F. Paillet, D. J. Rennie, S-T Moon, D. Gardner, T. Kamik, P. Sun, T. T. Nguyen, M. J. Hill, and K. Radhakrishnan, Memioglu, "A 100 MHz Eight-Phase Buck Converter Delivering 12A in 25 $mm^{2}$ Using Air-Core Inductors", IEEE 21th APEC, 727 (2007)
  6. S. Bae, Y. K. Hong, J. J. Lee, J. Jalli, G. S. Abo, A. Lyle, H. Han, and G. W. Donohoe, "High Q Ni-Zn-Cu ferrite inductor for on-chip power module", submitted to IEEE Transactions on Magnetics, May 2008
  7. I. Kowase, T. Sato, K. Yamasawa, and Y. Miura, "A planar inductor using Mn-Zn ferrite/polyimide composite thick film for low-voltage and large-current DC-DC converter", IEEE Trans. on Mag., 41, 3991 (2005)
  8. S. Prabhakaran, C. R. Sullivan, T. O'Donnell, M. Brunet, and S. Roy, "Microfabricated coupled inductors for DC-DC converters for microprocessor power delivery", 35th IEEE Power Electronics Specialists Conf., 6, 4467 (2004)
  9. P.-L. Wong, F. C. Lee, P. Xu, and K. Yao, "Critical inductance in voltage regulator modules", IEEE Trans. on Power Elec., 17, 485 (2002)
  10. T. Nakamura, "Snoek's limit in high-frequency permeability of polycrystalline Ni-Zn, Mg-Zn, and Ni-Zn-Cu spinel ferrites" J. of Appl. Phys., 88, 348 (2000)
  11. M. Nakano, M. Akase, H. Fukunaga, Y. Matsuo, S. Yabukami, M. Yamaguchi, and K. I. Arai, "Permeability in PLD-made Mn-Zn ferrite thin films by low-temperature process", J. of Magn. and Mag. Mater., MM, 242-245, 157 (2002)
  12. Z. Qian, G. Wang, J. M. Sivertsen, and J. H. Judy, "Ni-Zn ferrite thin films prepared by facing target sputtering", IEEE Trans. on Mag., 33, 3748 (1997)
  13. T. Kagotani, R. Kobayashi, S. Sugimoto, K. Inomata, K. Okayama, and J. Akedo, "Magnetic properties and microwave characteristics of NiZnCu ferrite film fabricated by aerosol deposition method", J. of Magn. and Mag. Mater., 290-291, 1442 (2005)
  14. N. Matsushita, M. Tada, M. Shigemori, and M. Abe, "High deposition rate obtained for spin-sprayed Ni-Zn ferrite films without using ammonia ions", IEEE Trans. on Mag., 40, 2817 (2004)
  15. S. Hashi, N. Takada, K. Nishimura, O. Sakurada, S. Yanase, Y. Okazaki, and M. Inoue, "Fabrication technique for over $10-{\mu}m-thick$ ferrite particulate film at room temperature", IEEE Trans. on Mag., 41, 3487 (2005)
  16. T. Kuribara, M. Yamaguchi, and K-I. Arai, "Equivalent circuit analysis of an RF integrated ferromagnetic inductor", IEEE Trans. on Mag., 38, 3159 (2002)

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