Fast and direct coupled-micro strip interconnect reduced-order modeling based on the finite-element method

Coupled-microstrip interconnect modeling including frequency-dependent effects (such as skin and proximity effects) is very important in high-speed digital circuits and microwave electronics systems. Two novel methods to model the coupled microstrip with a lumped equivalent circuit are proposed. The circuit model is obtained without using normal mode decomposition. Therefore, the circuit can be used in any excitation. We briefly review the stored energy equation for the inductance and power dissipation for the resistance when the interconnect consists of more than one signal conductor. In the first method, the rational function for impedance has common poles. Thus, an equivalent-circuit model is obtained in a fast and systematic way. In the second method, a more direct way of evaluating series impedance is proposed. Here, a more complicated method of pole selection leads to better accuracy in the frequency domain. A lumped-element equivalent circuit is obtained, which contains only series resistors, series inductors, and shunt capacitors. Hence, the circuit model should be very fast in transient simulation. Three examples are presented to demonstrate and validate the proposed methods.