Patent ID: 7777597
Filing Date: 2010-08-17
Classification: H03F,H03H

Abstract:
1. A radio frequency band reject filter comprising: a first acoustic resonator and a second acoustic resonator, the first and second acoustic resonators comprising either shunt resonators adapted to resonate substantially at respective resonance frequencies defining a rejection frequency band or series resonators adapted to anti-resonate substantially at respective anti-resonance frequencies defining the rejection frequency band; and a phase shifter connecting the first acoustic resonator and the second acoustic resonator and adapted to impart an impedance phase shift of between 45° and 135°; wherein the first acoustic resonator comprises one of a first plurality of acoustic resonators that are connected to the second acoustic resonator through the phase shifter; wherein the second acoustic resonator comprises one of a second plurality of acoustic resonators that are connected to the first acoustic resonator through the phase shifter; wherein the first plurality of acoustic resonators and the second plurality of acoustic resonators comprise different numbers of acoustic resonators.