Microfluidically Reconfigurable Metallized Plate Loaded Frequency-Agile RF Bandpass Filters

Microfluidically repositionable metallized plates have been recently introduced as a technique to realize frequency-agile bandpass filters with low insertion loss (IL) and wideband continuous frequency tunability. This paper utilizes a hybrid (circuit and electromagnetic simulation) model for time efficient simulations and introduces fourth-order bandpass filter designs for the first time to extend the applicability of the technique to higher order frequency-agile RF filter design. The paper introduces novel microfluidic channel and resonator configurations to demonstrate that the proposed filters can serve application specific footprint needs. By resorting to a selectively metallized plate approach, the reliability issue associated with synchronized movement of multiple metallized plates has been resolved. The filters are incorporated with micropumps to enable their automated control. Specifically, the concepts are demonstrated through design, fabrication, and testing of two fourth-order bandpass filters exhibiting different resonator arrangement layouts. The filters were measured to operate over ~ 2:1 (60%) frequency tuning range (0.8 GHz -1.5 GHz) with better than 4.5 dB IL, ~ 5% constant fractional bandwidth (FBW), and >40 dB out of band rejection implying a good agreement with the simulation based performance predictions. For the selected micropumps and investigated microfluidic channel layouts, the best tuning speed was measured to be 2.12 MHz per millisecond.