Planar, Double-Layer Magnetic Inductors for Low Power, High Frequency DC-DC Converters
Résumé
This paper presents the design and fabrication of micro-planar inductors with one and two magnetic layers, as well as the corresponding experimental results. Spiral inductors are suitable for low power (1 W) DC-DC monolithic converters. Sufficiently high switching frequency (>100 MHz) enables a System-In-Package assembly with the micro-planar inductors that could be used as a carrier of the active chip. Thick magnetic layers serve as a mechanical carrier and also present a double purpose of increasing the inductance value and absorbing electromagnetic interferences (EMI). Geometrical parameters are studied using an electromagnetic simulator for optimization purposes. A 500 nH spiral inductor with expected 140m RDC, 9mm2 footprint area is designed for operating at 100 MHz. A low-cost, labscale technology that is compatible with industrial clean rooms has been developed. Samples are tested using a LCR meter in the 10 kHz to 110MHz frequency range. The performances of the micro-inductors are compared to the predicted response of simulated equivalent model with good agreement.