Characterization of low impedance 3d coplanar waveguide interconnects for compact MMICs

Abstract

Low characteristic impedance coplanar waveguide (CPW) interconnects are desirable for microwave applications such as power FET's and photodiodes. In conventional planar MMICs, typical characteristic impedances are in the range of 40-100Ω, such that in order to realize 20Ω interconnect, one has to fabricate a very narrow slot width with a wider signal conductor width. As the objective is to achieve low characteristic impedance interconnects (<20Ω), the proposed techniques are by employing an additional metal layerto increasethe intrinsic distributed capacitance within interconnect. In this work, realization of low impedance 3D CPWinterconnect has been done by employing the overlapped metal techniques. The microwave characteristics are studied with different signal conductor widths and it has shown that the characteristic impedance as low as 10Ω can be achieved for MMIC interconnects with slot width of 15μm. This illustrates the great flexibility of the multilayer technology allowing various parameters to be achieved with small modifications in the design structure.