Self-switching vibrating micromechanical filter bank

Bridged MEMS-based micromechanical filters have been demonstrated that use a self-switching property of their dc-biased capacitive transducers to achieve zero-loss on/off filter switching without the need for lossy series switches, and with settling times down to 1.5 μs. By dispensing with the need for series switches in the signal path, a small bank of 0.087% bandwidth, 9-MHz beam-based filters has achieved programmable channel/band selection with only 3 dB of insertion loss, comprised entirely of filter loss (i.e., no switch loss), with switching times 7× faster than the typical 10 μs of some of the fastest RF MEMS switches, and without the high actuation voltages (>90V) and reliability issues often associated with RF MEMS switches. Higher frequency 155-MHz disk resonators achieve even faster switching speeds, with settling times down to only 430 ns. Equipped with this self-switching property, capacitively transduced micromechanical resonators are attractive candidates for realization of the switchable filter banks targeted for future wireless transceivers.