Symmetric multi-layer spiral inductor for use in RF integrated circuits

Abstract

A symmetric multi-layer inductor, providing an increased inductance of a conventional dual-layer inductor, exhibits a quality factor comparable to or better than that of a conventional single-layer inductor. The inductor includes a top metal patterned layer provided with a pair of groups of N number of metal lines, a bottom metal patterned layer, disposed between the substrate and the top metal patterned layer, provided with a pair of groups of N number of metal lines and an insulating material surrounding each of the metal patterned layers. In the inductor, the group of N number of metal lines on the each metal patterned layer and the other group of N number of metal lines on the same metal patterned layer are symmetric to each other with respect to an imaginary central line. Each of the metal lines has at least one via hole at one end thereof.