VHF phononic band gap band pass filters using coupled resonator acoustic waveguides (CRAW)

Among the functionalities required in high quality wireless communication devices is filtering. The ability to filter a subset of frequencies with sharp transition bands is one of the most demanding functions that micromechanical structures have a sharp edge over other technologies in wireless communication devices. In this paper we report the design, fabrication, and characterization a CMOS-compatible VHF bad pass (BP) filter element based on the phononic band gap (PnBG) of a phononic crystal (PnC) structure fabricated in silicon (Si). To our knowledge this is the first demonstration of the possibility of PnC filtering reported at such high frequencies. By coupling PnC resonators, BP filters are realized to function within the PnBG of the PnC. The BP filter is centered approximately at 140 MHz with a rational bandwidth of 7% and very sharp transition region characteristics.