Investigation of On-Chip Soft-Ferrite-Integrated Inductors for RF ICs—Part II: Experiments

We report the systematic study and design optimization of CMOS-compatible on-chip ferrite-integrated inductors, including detailed quantitative analysis by simulation and circuit modeling, new ferrite fabrication and characterization, ferrite-integrated-inductor design, measurement, and optimization. A new ferrite nanopowder-mixed-photoresist spin-coating/inkjetting technique is discussed. The design and characterization of ferrite-integrated inductors with various ferrite-filling structures are presented. Measurement shows substantial improvement of up to +160% in inductance (L) and + 220% in quality factor (Q) across the multigigahertz frequency spectrum with a self-resonance frequency (f ₀) over 20 GHz for the new ferrite-integrated inductors. This study clearly suggests that the new ferrite-integrated inductor technique is a potential solution to the realization of radio-frequency systems-on-a-chip requiring high-performance compact on-chip inductors. This work is presented in two parts. Part I discusses the design and simulation of ferrite-integrated inductors. This paper is Part II, presenting experimental results for material research and device implementation.