VO ₂ Switch-Based Tunable 3-D Cavity Filters

This paper presents the design and implementation of Vanadium Oxides (VO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>) switch-based tunable three-dimensional (3D) cavity filters. The proposed concept employs switched strip lines integrated with cavity resonators to tune their resonance frequencies. This eliminates the need to use variable/switched capacitors, which are known to degrade the loaded <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> of the filters over the tuning range. Combline filters and dielectric filters integrated with VO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> switches are designed, fabricated, and measured. The measurement results verify the tunability and feasibility of using the proposed tuning scheme to realize a relatively high-Q VO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> combline and dielectric resonator tunable filters that can maintain their <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> values over the tuning range.