Planar models of reconfigurable MEMS circuits

This paper presents a general procedure for the electromagnetic modeling of arbitrarily shaped reconfigurable planar circuits using RF microelectromechanical systems switches. In this model, the reconfigurable structure is represented by a linear time-invariant planar multiport, which is connected through internal ports to as many variable lumped-element circuits as the switches. Unlike conventional equivalent circuits, in this technique, the lumped elements represent only a small portion of the switch, and their values are not affected by the proximity of the switch to line discontinuities or to other switches. For this reason, the same values can be reused, with no substantial constraint, in the modeling of very different reconfigurable structures. For any type of switch, the lumped elements are deduced from the experimental or simulated frequency response of a simple prototype. The (arbitrarily shaped) environment of the switches is taken into account in the planar multiport, which is modeled by using very efficient 2-D electromagnetic simulators. Therefore, a lot of different geometries can be easily experimented and the corresponding frequency responses can be readily calculated for any set of the switch states. Index Terms--Co-simulation, electromagnetic modeling, RF microelectromechanical system (MEMS) switches.