Simple CAD formula for inductance calculation of square spiral inductors with grounded substrate by duality and synthetic asymptote

This Letter gives simple CAD formulas for the inductance calculation of a square spiral inductor on a grounded substrate, by duality and synthetic asymptote at low frequency. The average errors of the formulas are less than 2%. The formulas also give good physical insights to the layout of the spiral inductor. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 93–96, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10383