Twisted inductors for low coupling mixed-signal and RF applications

Abstract

Parasitic magnetic coupling is a major design challenge for integrated circuit designers. Fundamentally, it originates in conventional spiral inductors because the magnetic field is not localized, extending far beyond the perimeter. This paper introduces a twisted winding scheme for inductors that increases the localization of the magnetic field, reducing parasitic magnetic coupling by as much as 3100X and the edge-to-edge spacing of inductors by 10X. These results are validated in a 0.18 mum CMOS process.