1 Introduction
Complex high-speed systems require 3-D electromagnetic (EM) methods [1], [2] as analysis and design tools. Large systems of equations are usually generated by the use of these methods and model order reduction (MOR) techniques are crucial to reduce the complexity of EM models and the computational cost of the simulations, while retaining the important physical features of the original system [3], [4]. Over the last years, the development of methods to build reduced order models (ROMs) of EM systems has been intensively investigated, with applications to interconnects, vias and high-speed packages [5], [6].