3-D microfabricated toroidal planar inductors with different magnetic core schemes for MEMS and power electronic applications

Micromachined toroidal planar inductors that have three different magnetic core structures have been designed, fabricated, and characterized for MEMS and power electronic applications. A plain ring core shows a high inductance value of 10 /spl mu/H in a low frequency range below 2 kHz, whereas both a ring core with an air gap and a spiral type core show higher inductance values in a high frequency range of 2 kHz-1 MHz. The inductors have a low resistance value of /spl sim/1.5 /spl Omega/ with total dimensions 4 mm/spl times/1.5 mm/spl times/120 /spl mu/m.