Fully Printed VO2 Switch Based Flexible and Reconfigurable Filter

Frequency reconfigurable filters are high in demand because they can cover multiple frequency bands. Another emerging trend is the flexibility of the electronic components, so that they are suitable for wearable applications. In this work, we demonstrate a frequency reconfigurable bandpass filter that has been fully-printed on a flexible Kapton substrate. The frequency reconfigurability has been achieved through a printable switch made of Metal-Insulator-Transition material Vanadium-dioxide (VO2). The switch is in OFF condition (insulating condition) at room temperature and turns ON (becomes conductive) at above 68C. The microstrip bandpass filter employs dual-mode resonators and can switch from 4.0 GHz to 3.7 GHz. The required thermal bias is provided through a printed heater on the backside of the filter. Due to the flexible Kapton substrate and the printing process, the filter is highly flexible and low cost. Measured results are promising and in good agreement with the simulation results.