Fundamental circuit technology for three-dimensional MMICs

A novel three-dimensional MMIC technology is developed to make highly integrated multifunctional MMICs. This paper describes its structure and features and various new transmission lines using the structure. Novel passive circuits, such as a quadrature hybrid, an in-phase power divider, and a balun, are demonstrated to highlight the advantages of the 3-D MMIC technology. In the last section, the design concepts of a low-noise amplifier, a variable gain amplifier, and an image-rejection mixer are also described. The highly integrated multifunctional MMICs and masterslice MMICs described in this special issue can be made using 3-D MMIC technology and these fundamental circuits.