• coupled-line method;
  • equivalent model;
  • inductance;
  • spiral inductor


This article presents a new equivalent circuit modeling methodology for circular-type spiral inductors in printed circuit board. The N-turn circular spiral inductor can be decomposed into an N-π equivalent circuit model, and each π model is comprised of a series inductor, series capacitor, and two shunt capacitors. Both the inductance and capacitance of the equivalent circuit are calculated by the proposed formulas, which are based on the electromagnetic theory. It has been demonstrated that the proposed equivalent circuit model of the spiral inductor is well matched in S-parameters as well as inductance values within 6% tolerance with measurement and electromagnetic field solver simulation. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:337–340, 2012; View this article online at DOI 10.1002/mop.27287