A tunable magnetic inductor

For integrated radio-frequency applications, tunable magnetic inductors are expected. A tunable magnetic inductor, based on magnetoimpedance effect, is presented in this paper. The proposed inductor is constructed with a magnetic inductor body, wound by an insulated coil, inducing a longitudinal dc bias magnetic field when a dc control current is flowing through. Formed by a conductive core coated by a high-permeability magnetic layer, the magnetic inductor body can be realized by either a thin-film structure or a composite wire. The reluctance models for both thin-film and composite wire structures are studied. A prototype tunable magnetic inductor, using a composite wire element, has been characterized. The results show that by varying the dc control current, the inductance L of the magnetic inductor can be tuned. The tunable range depends on the frequency of the current flowing through the inductor. A relative variation of inductance /spl Delta/L/L/sub 0/, up to 18% at low frequency (around 5 MHz), is achieved by applying a bias current of magnitude merely up to 15 mA. The quality factor varies from 5 to 17 in the measured frequency range. The proposed tunable inductor may be further optimized for high-frequency applications and has the potential to be realized in micro-electromechanical systems technology.

[1]  K. Kawabe,et al.  Planar inductor , 1984 .

[2]  K. Shirae,et al.  A novel miniature planar inductor , 1987 .

[3]  M. Ellis,et al.  Microassembled tunable MEMS inductor , 2005, 18th IEEE International Conference on Micro Electro Mechanical Systems, 2005. MEMS 2005..

[4]  Pavel Ripka,et al.  Giant magnetoimpedance sensors , 2001 .

[5]  Masahiro Yamaguchi,et al.  Magnetic RF integrated thin-film inductors , 2000, 2000 IEEE MTT-S International Microwave Symposium Digest (Cat. No.00CH37017).

[6]  J. Laskar,et al.  Reconfigurable RFICs for frequency-agile VCOs in Si-based technology for multi-standard applications , 2004, 2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535).

[7]  M. Okoniewski,et al.  RF MEMS tunable inductor , 2004, 15th International Conference on Microwaves, Radar and Wireless Communications (IEEE Cat. No.04EX824).

[8]  Vladislav Korenivski,et al.  Design of high frequency inductors based on magnetic films , 1998 .

[9]  Mark G. Allen,et al.  A fully integrated planar toroidal inductor with a micromachined nickel-iron magnetic bar , 1994 .

[10]  Vladislav Korenivski,et al.  Magnetic film inductors for radio frequency applications , 1997 .

[11]  P. Sen,et al.  Reconfigurable RFICs in Si-based technologies for a compact intelligent RF front-end , 2005, IEEE Transactions on Microwave Theory and Techniques.

[12]  Hiroshi Tomita,et al.  A magnetic thin film inductor and its application to a MHz switching dc-dc converter , 1994 .

[13]  Masahiro Yamaguchi,et al.  Characteristics and analysis of a thin film inductor with closed magnetic circuit structure , 1992, 1992. Digests of Intermag. International Magnetics Conference.

[14]  O. Ishii,et al.  Permeability measurement in the GHz range for soft-magnetic film using the M/C/M inductance-line , 1995 .

[15]  V. Lubecke,et al.  Self-assembling MEMS variable and fixed RF inductors , 2000, 2000 Asia-Pacific Microwave Conference. Proceedings (Cat. No.00TH8522).

[16]  Tetsuo Inoue,et al.  The effect of magnetic film structure on the inductance of a planar inductor , 1998 .

[17]  Yong Zhou,et al.  Fabrication of ultralow-profile micromachined inductor with magnetic core material , 2005 .

[18]  Amr A. Adly.  Controlling linearity and permeability of iron core inductors using field orientation techniques , 2001 .

[19]  M. Vroubel,et al.  Integrated tunable magnetic RF inductor , 2004, IEEE Electron Device Letters.

[20]  W. Roshen.  Analysis of planar sandwich inductors by current images , 1990 .

[21]  Kiat Seng Yeo,et al.  Extremely high-Q stacked transformer-type inductors for RF applications , 2003, 2003 International Symposium on VLSI Technology, Systems and Applications. Proceedings of Technical Papers. (IEEE Cat. No.03TH8672).

[22]  Cheolgi Kim,et al.  Effect of annealing on anisotropy field in Fe84Zr7B8Cu1 amorphous ribbons evaluated by giant magnetoimpedance , 1999 .

[23]  D. Pehlke,et al.  Extremely high-Q tunable inductor for Si-based RF integrated circuit applications , 1997, International Electron Devices Meeting. IEDM Technical Digest.

[24]  W. C. Ng,et al.  Development of high permeability nanocrystalline permalloy by electrodeposition , 2005 .

[25]  N. Saleh,et al.  Variable Microelectronic Inductors , 1978 .

[26]  L. C. Howlett,et al.  Wide frequency range sine wave VCO with a tunable inductor and capacitor , 1989 .

[27]  C.S. Tsai,et al.  Tunable wideband microwave band-stop and band-pass filters using YIG/GGG-GaAs layer structures , 2005, IEEE Transactions on Magnetics.

[28]  N. A. Buznikov,et al.  Current distribution and giant magnetoimpedance in composite wires with helical magnetic anisotropy , 2005, cond-mat/0502086.

[29]  T. B. Oh,et al.  Effect of magnetic field on the magnetic properties of electroplated NiFe/Cu composite wires , 2003 .

[30]  M. Daneshmand,et al.  RF MEMS devices , 2003, Proceedings International Conference on MEMS, NANO and Smart Systems.

[31]  R. Soohoo,et al.  Magnetic thin film inductors for integrated circuit applications , 1979 .

[32]  S. Zhou,et al.  Large stress-resistance effect at high frequencies in Co68.5Fe4.5Si12B15 amorphous ribbon , 2002 .

[33]  Vladislav Korenivski,et al.  GHz magnetic film inductors , 2000 .

[34]  Imed Zine-El-Abidine,et al.  A new class of tunable RF MEMS inductors , 2003, Proceedings International Conference on MEMS, NANO and Smart Systems.

[35]  A. Pohm,et al.  Magnetization in minimum geometry M-R heads with multilayer films , 1984 .

[36]  Xi-Qing Sun,et al.  A micro variable inductor chip using MEMS relays , 1997, Proceedings of International Solid State Sensors and Actuators Conference (Transducers '97).