Georgia Tech inventors have created an acoustically coupled thin-film piezo resonator system in which all the resonators are implemented on a monolithic resonant structure. These coupled resonators are used in a signal processing to realize band-pass filters. The monolithic thin-film-piezoelectric acoustic filters includes a resonant structure that is released from and supported by a substrate that comprises a thin-film piezoelectric layer disposed between a lower electrode and a plurality of electrically isolated upper electrodes.
- Offers better out-of-band rejection
- Allows for large isolation in a low-order coupled system
- Microwaves acoustic materials and devices
- Devices where multiple-band data transfer channels are required in small form-factor
Thin-film piezoelectric bulk acoustic resonators (FBAR) are utilized in the front-end of some transceiver circuits at GHz frequencies. Typically, a number of FBAR resonators are electrically connected in a ladder configuration to provide low-loss high-order filters with a very sharp roll-off skirt. To provide adequate out-of-band rejection, the number of resonators in the coupling chain of electrically-coupled filters should be considerably large (between 4 to 10). Given the relatively large size of each resonator, electrically coupled FBAR filters span over a large area, and may not offer integrated solutions for covering dispersed frequencies in a wide band. The size of the filter is of greater importance in emerging applications where multiple-band data transfer channels are required in a small form-factor.