On-Chip Coupled Solenoid Inductors for Integrated Power Conversion

Magnetic core inductors with a sufficiently high coupling factor
${k}$
are critical for interleaved dc–dc converters. In current work, solenoid coupled inductors with a joint magnetic core were designed and fabricated to boost
${k}$
while preserving the hard-axis excited characteristic. Devices were optimized based on a closed-loop magnetic reluctance model. Test results evidence a high coupling coefficient of 0.42. Meanwhile, a large
${L}/{R}_{dc}$
ratio of 295 nH/
$\Omega $
and a high saturation current of 1.87 A have been achieved. The performance of the coupled inductor has been calculated for a standard 1.8–0.9-V interleaved converter and a high efficiency ~96% can be obtained across a wide range of phase currents between 0.3 and 1.6 A.