Effect of differently shaped spiral inductors on micro power integrated circuit

Abstract

This paper investigates the impact of parasitic effects on the performance of on-chip planar spiral inductors for DC-DC converter applications, focusing on three geometries: square, hexagonal, and octagonal. Detailed electromagnetic simulations in MATLAB are employed to analyze the frequency-dependent behavior of key parasitic components, including ohmic resistance (Rs), substrate resistance (Rsub), oxide capacitance (Cox), and substrate capacitance (Csub) across a frequency range of 1 GHz to 10 GHz. The study reveals that the octagonal spiral inductor outperforms the others, demonstrating a 29% reduction in ohmic resistance at 1.5 GHz compared to the square geometry and achieving the highest substrate resistance, which helps reduce current leakage. Additionally, the octagonal inductor exhibits the lowest parasitic capacitance and a high-quality factor, peaking at 30 at 4.2 GHz. These results underscore the significant impact of inductor geometry on minimizing energy dissipation and electromagnetic interference, positioning the octagonal spiral inductor as a compelling choice for enhancing efficiency and miniaturization in DCDC converter designs.