TRANSFORMER FOR MONOLITHIC MICROWAVE INTEGRATED CIRCUIT

摘要

A passive transformer which can be formed in an MMIC having a plurality of first-layer wirings formed on a substrate so that each of the first-layer wirings intersects a desired virtual line on the substrate; an insulating film for covering a substrate surface on which the first-layer wirings are formed; and a plurality of second-layer wirings formed on the insulating film so that each of the second-layer wirings intersects the virtual line and has opposite ends respectively connected to different ends of the first-layer wirings through contact holes. An inductor element having a spiral structure along the virtual line constitutes the first-layer wirings the contact holes and the second-layer wirings. The opposite ends of the inductor element are primary electrodes, and one end and a desired intermediate point of the inductor element are secondary electrodes. Because the transformer has such a structure, a three-dimensional coil can be formed on the substrate so that the transformer can be formed in an MMIC.