Miniaturized 90/spl deg/ hybrid circuit using quasi-distributed TFMS line

Abstract

In this paper, very miniaturized 90/spl deg/ hybrid circuit using quasi-distributed TFMS line is described. In a planar formed conventional MMIC's, the passive circuits such as 90/spl deg/ branch-line hybrid has occupied a large chip area. Therefore, it is strongly desired that the chip area is more miniaturized. For increasing integration level, the three-dimensional (3D) MMIC has been developed. In the 3D MMICs, meander-like lines are realized easily and many metal-insulator-metal (MIM) capacitors can be loaded on transmission lines. By the 3D MMIC topology, a transmission line composed of high impedance thin film microstrip (TFMS) lines and MIM capacitors are realized easily. This type TFMS transmission line is called "quasi-distributed thin film microstrip (QD-TFMS) line". A very small 90/spl deg/ branch-like hybrid using the QD-TFMS lines is realized. The fabricated 9/spl deg/ branch-like hybrid size is more than 80% smaller than that of conventional one compose of meander-like transmission lines in area.