Monolithic MEMS T-type Switch for Redundancy

This paper presents a novel approach to monolithically implementing RF MEMS T-type switches for redundancy switch matrix applications. The T-type switch performs three operational states: two turning states and one crossover state. A six-mask fabrication process is adapted to fabricate the proposed design. Novel RF circuits were used to implement the entire system, including series contact cantilever beams, RF crossover, 90 degree turns and four-port cross junctions. The measured results for the entire T-type switch demonstrate an insertion loss of 1.5dB, a return loss of better than -20dB and an isolation higher than 28dB for all states for frequencies up to 30GHz. To our knowledge, this is the first time an RF MEMS T-type switch has ever been reported. I. INTRODUCTION Microwave switches are very often used as basic building blocks for redundant networks in satellite communication where high reliability is desired. A redundant network provides the required connection to spare components such that a full functionality of the system is maintained in case of any failure. A common example of that is the malfunctioning of an RF amplifier in satellite payloads where a redundancy network is used to route the signal to a spare component. Satellite payload switching networks currently use semiconductor and electromechanical technologies. In general, RF electro-mechanical switches are used as they can provide very good RF performance compared to their semiconductor counterparts. These switches are usually very bulky, heavy and capable of switching only at a low speed. Although switching time is not a concern in redundant networks, but the weight and size are major drawbacks especially in satellites where mass reduction is critical.