Wideband Tunable Radio Frequency Integrated Circuit Inductors Integrated With Domain-Patterned Permalloy

For wideband frequency-agile radio frequency (RF) integrated circuits, tunable components are essential. It has been a great challenge in RF electronics to utilize a magnetic tunable inductor for ultrawideband applications. This letter demonstrates an electrically tunable RF inductor encompassing a broad range of frequencies from 4 to 20 GHz. This is achieved by integrating domain-patterned Permalloy of various thicknesses, such as 20, 60, and 92 nm. There is a performance boost of the inductor, and a tunable inductor is achieved by applying dc current. Experimental results show that amongst all the Permalloy patterns,
$11\,\mu\text{m}\times 13\,\mu\text{m}$
provides the highest inductance tunability of 15.8% at 20 GHz for 60 nm patterns, 10.8% at 15.1 GHz for 92 nm, and 4.3% at 15.7 GHz for 20 nm. This is the highest inductance tunability obtained so far for spiral inductors integrated with 60 nm Permalloy patterns using the dc bias method. The 15.8%, 10.8%, and 4.3% inductance tunability provides 8%, 5.7%, and 2.1% frequency tuning correspondingly.