Slow-Wave and Coplanar Monolithic GaAs Circuits

The major results of a study aimed at reducing the monolithic microwave circuit size are presented. The paper first reports the design and performances of new low-coupling coplanar circuits, which are suitable for both monolithic and hybrid applications and show a very flat coupling and a high directivity over a broad frequency range (e.g., 5 + 13 GHz). Then, experimental results and design data are presented for new low-size slow-wave couplers. Finally, the practical use of the slow-wave approach for overcoming some well known problems in the monolithic circuit design is described and the performances of a two-stage medium power monolithic amplifier, using a slow-wave line length in the interstage matching network, are stressed.