Development and Experimental Verification of an Electrical Model of a Doubly Wound Planar Circular Spiral Inductor

This article presents the development of an electrical model of a doubly wound planar (DWP) circular spiral inductor. Closed-form models for substrate capacitance, adjacent metal capacitance, and inter-spiral mutual inductance of this structure are developed, which have, so far, not been addressed in the literature. The proposed developed model presented in this article is applicable to any dielectric substrate. As an example, this inductor is fabricated on a glass-epoxy FR4 dielectric substrate, where close agreement is observed between the analytical model and experimentally measured inductance, over a broad range of frequencies, up to the UHF band (900 MHz). The proposed model can extend known existing planar inductors into symmetric two-terminal structures and can be used for circuit applications for a broad range of frequencies.