Handling RF Power: The Latest Advances in RF-MEMS Tunable Filters

摘要

Tunable RF/microwave filters are particularly promising components in modern multifunctional communication systems and radars. While resonator quality factor (Q), in-band insertion loss, out-of-band rejection, tuning range, and size/weight/volume/cost are often among the first features to be specified for a new filter design, a series of other factors including power handling, power consumption, linearity, response speed, reference impedance, analog versus. digital tuning, temperature stability, and immunity to vibration/shock can be equally critical attributes depending on the application. Achieving satisfactory performance with respect to all these requirements is a non-trivial task and has hindered the adoption of tunable filtering technology in commercial and defense systems particularly when low-power consumption is of critical importance. Recent developments in RF-MEMS tunable filter technology have allowed significant improvements in many of the previously mentioned factors [1] including much improved power handling. This paper discusses the latest advances in this area on both continuously tunable RF-MEMS devices, and digital-like tuned devices. While the emphasis of coverage is on fundamental understanding of power handling issues, relevant trade-offs are also outlined throughout the different sections.