Digitally-tunable MEMS filter using mechanically-coupled resonator array
This paper reports on the design of a bandwidth-tunable RF MEMS filter using a series-coupled array of dielectrically-transduced square-extensional mode resonators. The proposed digital tuning scheme provides channel-agility and bandwidth granularity for analog spectral processors and RF spectrum analyzers. The resonators and filters are fabricated on the 3 μm thick device layer of a heavily doped SOI wafer with a 100 nm thick silicon nitride film sandwiched between the polysilicon electrodes and the silicon device layer. A 511 MHz overtone square-extensional mode resonator is demonstrated with a quality factor (Q) of 1,800 in air and motional impedance (RX) of 1.1 kΩ. An array of four such resonators is coupled mechanically to form a channel-select filter with 1.4 MHz bandwidth at 509 MHz center frequency. By switching the DC-biasing scheme, the filter is split into narrower high and low sub-bands, each 700 kHz wide.
IEEE 21st International Conference on Micro Electro Mechanical Systems (IEEE MEMS 2008)
Hengky Chandrahalim, and Sunil A. Bhave, "Digitally-tunable MEMS filter using mechanically-coupled resonator array," IEEE International Conference on Micro Electro Mechanical Systems, 2008, pp. 1020-1023.