Inductor over MOSFET: Operation and theoretical study of a CMOS RF three-dimensional structure

In this paper we examine the operation of a structure that consists of an integrated inductor placed over a MOSFET within the same silicon die. This setup forms a single-chip, three-dimensional analog RF topology and was firstly introduced by the authors in 2002. The structure takes advantage of an idle metal layer above active circuits and uses it for the implementation of an inductor. As a consequence, the total area of the system´s analog part shrinks, the integrated inductor usage becomes more cost effective: but the interference between inductor and transistor increases.