Embedding Epitaxial VO2 Film to Switchable Two-Band Filter on the Surface Acoustic Waves

The paper proposes a tunable bandpass filter, the operating frequency of which in the range of 600–800 MHz is regulated by voltage. It is performed on a piezoelectric substrate made of lithium niobate and contains four parallel acoustic channels formed by two input interdigital transducers (IDTs), two multi-strip directional couplers and two output IDTs with the ability to switch each pair of acoustic channels with its independent vanadium dioxide film switch provides attenuation between channels of at least 70 dB. By using a special switch design based on a vanadium dioxide film and a coupler, we were able to reduce the control voltage to 0.1 V. The width of the vanadium dioxide film is no more than two periods of input IDT, which eliminates an increase in the SAW attenuation of s with an increase in the operating frequencies of the filter.