Fully printed resonance-free broadband conical inductors using engineered magnetic inks

Abstract

The current technologies of 3D printing have a huge potential in the domain of printed radio frequency (RF) electronic components, such as resistors, capacitors, inductors, and transmission lines. In this paper, we present the design, fabrication, and characterization of fully 3-D printed conical inductors for broadband applications. The cores of these conical-shaped inductors were all printed by engineered magnetic/dielectric materials: the first one with a polymer core was printed by the aerosol-jet (AJ) printing technology as a reference, the second one with an iron-cobalt core fabricated by a paste-extrusion (PE) method using our developed iron-cobalt-based magnetic ink, and the third one with a core fabricated (by the PE method) using iron-based powder. The conical inductor was placed at a 45° angle by mounting it on a lattice support structure, and this configuration ensured a reduction of the parasitic capacitance between the inductor and the substrate. As a result, it was possible, to achieve a resonant-free broadband performance beyond the Ka-band (26.5–40 GHz), thereby outperforming the commercial off-the-shelf (COTS) products. Numerical simulations were also performed to explain the inductor performance and pinpoint the optimal model parameters. As suggested by the lumped circuit model, the operational frequency of the fully 3D printed iron-powder-based-core inductor could be as high as 67 GHz, which is nearly two times larger than the commercial iron core inductor.