Micro Electro-Mechanical System (MEMS) mainly includes two parts, sensor and resonator. Micro resonators
are widely applied in the radio frequency (RF) field for its high isolation and low loss. The principles of micro resonators
are introduced firstly, including comb resonator, beam resonator, disk resonator, film bulk acoustic resonator (FBAR),
cavity structure resonator, and surface acoustic wave resonator (SAW). The applications of micro resonators secondly are
discussed, such as in the filter, duplex, sensor, mixer, and oscillator. The filter character of micro resonators is analyzed.
The frequency range and Q value of micro resonators are discussed too. Function of frequency conversion, micro resonator
work in different frequency bands, will be a new development direction of micro resonator, besides high frequency,
high Q, and wide bandwidth. In this article, various patents have been discussed.