Design and fabrication of integrated solenoid inductors with magnetic cores

Integrated solenoid inductors with magnetic core were designed and fabricated. An inductance above 70 nH was achieved while keeping the coil resistance below 1 Omega and the device area below 1 mm². The inductance of the magnetic inductor was more than 30 times that of the air core inductor of the identical geometry, and the inductance density reached above 200 nH/mm². Comparison with the planar spiral inductor shows that the solenoid inductor is significantly more efficient when the magnetic core is used. Our results indicate that integrated magnetic inductors suitable for mobile power conversion and RF system-on-chip circuits can be reliably designed and fabricated.