Dynamic monitoring of ohmic contact RF MEMS switches
Abstract
RF system complexity is steadily increasing due to demands for multiband and multifunction operation within a single device while maintaining or reducing size, cost, and power consumption. To combat this, efforts are ongoing to develop reconfigurable RF subsystems. RF MEMS switches comprise a crucial building block for such systems. However, cost and reliability concerns have hindered their widespread adoption. In this work, an ohmic contact RF MEMS switch is developed utilizing single-crystal-silicon (SCS) as the structural material while maintaining state-of-the-art performance. Unlike thin-film metals commonly employed in RF MEMS switches, SCS is essentially defect-free and has well-known and repeatable material properties. This makes the switch design insensitive to process variations and amenable to high- yield manufacturing. Measured devices exhibit on state insertion loss of less than 0.3 dB and off state isolation of higher than 30 dB up to 40 GHz and switching time under 4 microseconds. This switch is then used as a repeatable platform for developing an ultra-low-power (60-250 microwatt) IC based in-situ real-time monitoring technique for RF MEMS switch dynamics. The ability to record extremely small displacement bounces (<20 >nm) alongside the entire settling event with 99% accuracy in determining contact timing relative to LDV measurements is demonstrated experimentally. Changes in dynamic behavior of RF MEMS switches over lifetime operation are then utilized as a readily and simply observable method of failure prediction for a commercially available device. Rapid increases in the number of bounces are observed which indicate approximately 50-75% of total operation has elapsed.
Degree
Ph.D.
Advisors
Peroulis, Purdue University.
Subject Area
Electrical engineering
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