K/Ka-band coplanar waveguide directional couplers using a three-metal-level MMIC process

Two novel types of coupled line structures have been realized on GaAs monolithic microwave integrated circuits to obtain 90?? couplers operating at a center frequency of 24 GHz. Both of the couplers are made up of either two or three conductive layers to improve the coupling. The aim is to achieve compact couplers with smaller aspect ratios and to decrease the losses due to field crowding on the edges. Both couplers have achieved good matching and coupling. The simulation is carried out on the electromagnetic simulator em (a trademark of Sonnet Software Inc.).