Shunt capacitive switches based on VO2 metal insulator transition for RF phase shifter applications

This paper presents a wide-band RF shunt capacitive switch reconfigurable by means of electrically triggered Vanadium Oxide (VO2) phase transition to build a true-time delay (TTD) phase shifter. The concept of VO
₂
-based reconfigurable shunt switch has been explained and experimentally demonstrated by designing, fabricating and characterizing an 819 μm long unit cell. The effect of bias voltage on losses and phase shift has been studied and explained. By triggering the VO
₂
switch insulator to metal transition (IMT) the total capacitance can be reconfigured from the series of two metal-insulator-metal (MIM) capacitors to a single MIM capacitor. Higher bias voltages are more effective in this reconfiguration and give a higher phase shift. The optimal achievable performance has been shown heating the devices above VO
₂
IMT temperature. A maximum of 16° per dB loss has been obtained near the design frequency (10 GHz).