Digitally tunable input filter unit for LTE bands

This paper deals with the design of the fast tunable filter unit which is intended to be used in combination with a reconfigurable multiband antenna. Proposed filter unit combines classical microstrip technology with digitally tunable capacitors based on the state of the art semiconductor and micromechanical technology. The design of the filter unit is described and its performance is verified by simulations. Results are compared with an equivalent lumped element band pass filter. The tuning performance of the filter-antenna combination is demonstrated.