Design, fabrication and testing of sandwich coupled inductors

A planar coupled inductor having sandwich coil structure is fabricated using MEMS microfabrication techniques. The structure of the inductor coil is designed to achieve high coupling and high winding number with a relatively small coil area. In this work, the structure is fabricated by bonding two planar on-chip coil fabricated on two different substrates. This method can replace the conventional via connections that cause various problems in output pads interconnection. The functionality of the fabricated device was tested, while the basic characteristics of the fabricated coil were measured at wide range of operating frequency using cascade GSG probe and compared with the simulation. For measurements up to 1?GHz, three resonance frequencies, inductance of 35?nH and resistance of as low as 25?Ω were observed. The results show that the proposed technique is a promising alternative method for fabricating a simple and cost effective 3-D coupled inductors.