RF microwave switches based on reversible metal semiconductor transition properties of VO2 thin films : an attractive way to realise simple RF microelectronic devices

Microwave switches in both shunt and series configurations have been developed using the semiconductor to metal (SC-M) transition of vanadium dioxide (VO2) thin films deposited by in situ pulsed laser deposition on C-plane sapphire and SiO2/Si Substrates. The influence of geometrical parameters such as the length of the switch is shown. The VO2-based switches exhibit up to 30-40 dB average isolation of the radio-frequency (RF) signal over a very wide frequency band (500 MHz-35 GHz) with weak insertion losses, when thermally activated. Furthermore, they can be electrically activated. Finally, these VO2-based switches are integrated in the fabrication of innovative tunable band-stop filters which consist of a transmission line coupled with four U-shaped resonators and operate in the 9-11 GHz frequency range. Its tunability is demonstrated using electrical activation of each VO2-based switch.