Synthetic Asymptote Formulas of Equivalent Circuit Components of Square Spiral Inductors

Abstract

This paper derives simple computer-aid design (CAD) formulas of the components of the equivalent circuit of square spiral inductors on a microstrip substrate. The circuit components are the main inductor, its capacitors to ground, and resistance. The formulas are simple synthetic asymptotes constructed from duality and analytical moment method, and give clear physical insights. Compared with IE3D, a commercial software by Zeland, the errors of |S ₁₁| and |S ₂₁| are generally less than 2%.