Order selection for loewner matrix based macromodels for accurate macromodeling of distributed high-speed modules from limited number of full-wave S-parameter data

Recently, Loewner Matrix (LM) method was introduced for generating time-domain macromodels based on frequency-domain measured parameters. For the case of lumped systems the order is clearly defined and is detected easily by the LM algorithm. However, for the case of distributed systems with a theoretically infinite number of poles, an optimum order is not easily obtained. In this paper we propose an order selection method for distributed systems defined by simulated or measured S-parameters. The advantages of the proposed approach are illustrated using numerical examples.