Millimeter-wave MEMS tunable low pass filter with reconfigurable series inductors and capacitive shunt switches

In this paper, a new type of reconfigurable inductor is proposed for mm-waves based on the reconfiguration of slow-wave coplanar waveguide (CPW) lines using multiple-contact switches. It is then employed together with micro-electro-mechanical systems (MEMS) capacitive shunt switches to realize a reconfigurable low-pass filter, where the values of both inductors and capacitors are changed independently to achieve optimum filter characteristics. The measured 3-dB cut-off frequency of the reconfigurable low-pass filter changes from 53 GHz to 20 GHz while maintaining Tchebycheff low-pass prototype characteristics. The out-of-band rejection characteristics are also improved in this way. To our knowledge, this is among the first demonstrations that both types of MEMS contact switches and capacitive switches are used simultaneously to construct a monolithic tunable filter with independent L/C controlling capability.