Fast thin film vanadium dioxide microwave switches

A new concept in microwave and millimeter-wave switching structures is demonstrated. The switch is built on a GaAs substrate and is compatible with IC technology. The approach used to implement the concept is to place a variable-resistance element spanning a very short gap (compared to the width of the line) on a metal transmission line. Switching the gap material from the high resistance state to the low resistance state turns the line from an open circuit to the connected state. The topics discussed include the material system used, a specific demonstration of a microwave switch using this system, possible applications of the switch, and its present limitations and how they could be overcome. A switch is built which at 40 GHz has an insertion loss of less than 1 dB in the on-state and more than 12 dB in the off-state. Switching time is under 30 ns.<>