Acoustic resonator including an electret, and method for manufacturing said resonator, application to coupled-resonator switchable filters

摘要

The resonator has electrodes (24, 26) arranged on both sides of a piezoelectric layer (30). An electret layer (32) is provided between the electrodes for applying permanent electric field to the piezoelectric layer, where the piezoelectric layer has electromechanical properties. The electret layer is made of piezoelectric material, crystalline and amorphous, where the electret layer has permanent electric loads (28). A substrate is provided in the cavity. An independent claim is also included for a method for fabricating an acoustic resonator.