The Effects of a Ground Shield on the Characteristics and Performance of Spiral Inductors

The frequency dependence of the model parameters of patterned ground shield (PGS) inductors in large part is explained as a consequence of modeling a distributed system with a lumped model. The etrects of PGS shape and material on inductor characteristics have been examined and explained. There is an optimum area for a PGS to maximize Q. Usingan n⁺ buried/n-well PGS the peak Q is improved by ~25% from that of an inductor without a PGS whlle only slightly changing L and Cp in comparison to inducton with other PGSs. Having a PGS does not signif- icantly improve isolation between adjacent inducton wben isolation is limited by mapetic coupling since a PGS is specifically designed to limit termination of magnetic fields.