Novel, very small-size multilayer MMIC's using miniature microstrip lines on a thin dielectric film, as well as the features of the multilayer structure, are presented. Very narrow-width thin-film transmission lines, meander-like configurations, line crossovers, and vertical connections, which are effective for significant chip-size reduction and flexible layout, are realized and utilized in a 2.5-3 µmN-layer dielectric film structure. 180-degree and 90-degree hybrids and umltiport Wilkinson dividers, which are implemented in small areas of 0.1 mm2 and 1.7 mm2, are presented. Furthermore, layout flexibility in the multilayer structure is demonstrated by implementing distributed amplifiers into the layers.

This paper proposes an MMIC image rejection mixer and an MMIC balanced mixer employing multilayer microstrip lines and high-electron-mobility-field-effect-transistor (HEMT)s with a LUFET configuration (line-unified HEMT module). The advantage of the mixers is remarkable chip size reduction by the combination of the two technologies. The multilayer microstrip line, in which one microstrip line is placed upon another, is used for stacking passive circuits, e.g. a 90 hybrid and distributed lines, to reduce the chip-area occupied by transmission lines, and to allow flexible line allocation. The line-unified HEMT module provides all functions required for in-phase/out-of-phase power divider/combiners in HEMT electrode and unified coplanar lines configuration. A 29-32 GHz image rejection mixer and a 3-27 GHz balanced mixer are realized in only 1.6 mm 1.0 mm and 1.8 mm 1.2 mm MMIC chip size, respectively.