A MMIC lumped element directional coupler with arbitrary characteristic impedance and its application

In this paper the design technique for MMIC lumped element directional couplers, based on arbitrary termination impedance, is described. Arbitrary impedance terminations allow matching the linear and nonlinear elements to the coupler without the requirement of transformer networks. The technique's capability is demonstrated through the design of a single balanced mixer prototype at 1.8GHz for which measured and simulated data are provided.