CHARACTERISTICS OF A COPLANAR WAVE-GUIDE HEMT MOUNT ON GAAS SUBSTRATE

In a special integrated coplanar waveguide HEMT mount, designed for a wide band (1-60 GHz) on-wafer measurement of the characteristics of HE MTs on GaAs, significant power loss as high as 30% of the input power over a range of frequencies is observed. This power loss is mainly att ributed to the radiation through two via holes connecting the coplanar waveguide ground planes to the backside metallization in the mount. B ased on this assumption, an approximate theoretical model is developed to substantiate the experimental observations.