Design and Characterization of High Quality-Factor Inductors for Wireless Systems Compatible With Flexible Large-Area Electronics

• Published in: IEEE journal on flexible electronics Vol. 3; no. 6; pp. 234 - 241
• Main Authors: Ma, Yue, Wagner, Sigurd, Verma, Naveen, Sturm, James C.
• Format: Journal Article
• Language: English
• Published: IEEE 01.06.2024
• Subjects: 5G/6G; flex compatible; Inductance; Inductors; Internet of Things (IoT); monolithic integration; planar inductor; Q-factor; Radio frequency; Silver; Substrates; Thin film transistors
• ISSN: 2768-167X; 2768-167X
• DOI: 10.1109/JFLEX.2024.3379975

Resonant operation, exploiting high quality-factor planar inductors, has recently enabled gigahertz (GHz) applications for large-area electronics (LAE), providing a new technology platform for large-scale and flexible wireless systems. This work first presents the design, analysis, and characterization methodology of flex-compatible large-area planar inductors. Specifically, three distinct radio frequency (RF) inductor characterization methods are experimentally demonstrated and compared, with the most accurate method among them (i.e., <inline-formula> <tex-math notation="LaTeX">S </tex-math></inline-formula>-parameters in a two-port configuration) demonstrating a record-high quality factor of up to <inline-formula> <tex-math notation="LaTeX">\sim 65 </tex-math></inline-formula> in the 2.4-GHz frequency band. Enabled by accurate characterization, key inductor design considerations regarding the resistive loss due to inductor's metal traces are then discussed. Finally, a case study of the recently demonstrated LAE resonant switch shows the potential of these high-performance inductors towards large-area and conformal wireless systems for integrated Internet of Things (IoT) and 5G/6G applications.