A tunable CPW spurline filter employing distributed MEMS switches

The present work uses MEMS switches for electrostatic control of centre frequency and bandwidth in a Coplanar Waveguide (CPW) Spurline filter. The filter consists of short end series stub resonators etched in the signal line of CPW. MEMS capacitive shunt switches are loaded across the stubs and across the inter resonator spaces and actuation of the switches alter the effective electrical length of the stub sections and the inter resonator spaces. This leads to variation in frequency response. The design of the MEMS switches is also presented. This is based on modeling the variation in effective electrical length due to the loading by the MEMS shunt switches. The switch capacitances over stubs are calculated with a reduced effective width to account for the etched stubs.