Highly reconfigurable bandpass filters using microfluidically controlled metallized glass plates

A novel microfluidic-based approach for realizing highly reconfigurable bandpass filters is presented. The filter topology employs open loop resonators that are capacitively loaded with metallized glass plates. By using microfluidics, the metalized glass plates can be repositioned over the resonators to control the amount of capacitive loading and provide the frequency tuning capability. For the presented two-pole filter, a thin film based fabrication technique is employed to realize a separation of 25μm between the metalized plates and the printed open loop resonators to maximize the capacitive loading and associated tuning range. The shape of the microfluidic channel and resonators are designed to operate the filter with a single micropump unit with near constant fractional bandwidth performance. Specifically, the filter exhibits a 50% frequency tuning range from 1.5GHz down to 0.9GHz. The insertion loss is lower than 1.7dB in the pass band and agrees well with the simulation based results.