Wideband active microwave isolators using GaAs MMIC technology

The paper is concerned with circuit designs for wideband microwave isolators realised as monolithic microwave integrated circuits using depletion-mode GaAs MESFETs. An unbalanced version of a previously published balanced design is shown to have an interesting property of an approximately linear transmission function but the port impedances remain nonlinear. A previously published general circuit synthesis method is used to implement an isolator with transmission function and port impedances both of which are linearised. Measurements on a GaAs MMIC implementation are presented