Low-impedance matching: The straight stub solution

The requirement of low impedances in most integrated circuits is solved through the use of straight stubs, treating them as one-dimensional structures. The inadequacy of that approach can be overcome by adopting a complete modal theory—and the corresponding synthesis tools—developed to characterize those electromagnetic aspects deriving from the “planarity” of the structure. The simulations performed adopting both commercial CAD packages and the modal approach have been compared with some experiments and the need for a better characterization for the presently available cross-junction element models has been pointed out.