US Patent 7138889 Single-port multi-resonator acoustic resonator device

A single port multi-resonator acoustic resonator device (200, 300, 400, 490) possesses an input impedance that exhibits precisely designed electrical resonances. The device contains at least three parts: a transducer/resonator (201, 301, 401. 491) used both to interface to an external electrical circuit and to transform electrical energy into mechanical (i.e. acoustic) vibrations (and vice versa), and also function as a resonator; a mechanical (i.e. acoustic) resonator (203, 303, 460, 480) and an acoustic coupler (202, 302, 404, 494) that controls the acoustic interaction between the transducer/resonator and the mechanical resonator.