DC-Contact Cantilever RF-MEMS Switches at Millimeter-wave Frequencies

The strong demand for more flexible yet lower power and light-weight RF systems, for both military and commercial applications, has given rise to the development of a technology that can greatly reduce power consumption and improve performance. RF Micro-Electro-Mechanical systems (RF-MEMS) is the integration of mechanical micro-structures on a common substrate, through micro-fabrication technology, to carry out the functionality of switches and varactors from RF to millimeter-wave frequencies. RF-MEMS technology with low-loss, small size, light-weight, high linearity and low power consumption provides an innovative approach in the development of highly efficient miniaturized modern RF/microwave/millimeter-wave systems.;This research is focused on developing high performance DC-contact RF-MEMS switches for millimeter-wave applications. The design, fabrication and measurements of a dielectric-free broadband DC-Contact cantilever switch are presented. A new low-stress fabrication process is developed for this compact RF-MEMS device with a specific advance of yielding a flat profile for a relatively thin beam. The fabricated switches have demonstrated outstanding RF performance (insertion loss less than 0.5 dB and isolation better than 24 dB up to 50 GHz) and the capability of working at cryogenic temperatures (1.6--300 K). The temperature response of the switch RF performance and actuation is investigated and measurement results are presented. A switch time measurement and initial reliability test of 131 million cycles at 77 K were also done to characterize the performance of the switch in the vacuum ambient. A broadband SP4T switch was designed for millimeter-wave applications based on the compact SPST switch. Great RF performance (insertion loss< 1 dB 60 GHz, Isolation> 18 dB 60 GHz) and broad bandwidth (up to 75GHz) are also achieved with the fabricated SP4T switch. Finally, a 60 GHz 2-bit TTD phase shifter for the emerging 60GHz high data rate communications application has been demonstrated with high phase linearity and low phase error (< 1°).