SWITCHING OPTIONS: THE RIGHT FIT MIGHT COME WITH A LOSS

摘要

Whether you are building "big-iron" RF-test equipment or tiny, multiband mobile devices, you need to route RF and microwave signals among instruments and devices under test or between antennas and amplifiers. To accomplish that task, you can turn to various solid-state implementations, including SOI (silicon-on-insulator) devices andrnMEMS (microelectromechanical-system) switches, both of which vendors were touting at the June IEEE MTT-S (Microwave Theory and Techniques) International Microwave Symposium. Highly integrated bulk-CMOS devices represent another alternative. However,rnyou need to know when those options make sense as alternatives to the more traditional electromechanical, PIN-di-ode, and GaAs (gallium-arsenide) FET versions. Solid-state and MEMS switch-es take up much less real estate and have longer lifetimes than do electromagnetic switches. Further, SOI and MEMS devic-es can be easier to integrate than GaAs devices with other components. Before embarking on switch selection, however, you need to understand whether the specs of the device you select will meet your application requirements.