Patent ID: 8525620
Filing Date: 2013-09-03
Classification: H03H

Abstract:
1. A bulk acoustic wave (“BAW”) resonator filter, comprising: an input of the BAW resonator filter for receiving an electrical signal; a blocker inductor, coupled to the input, that increases a bandwidth associated with the BAW resonator filter and improves above-band frequency rejection by the BAW resonator filter; a first series solidly mounted resonator (“SMR”) BAW resonator, coupled to the blocker inductor, that at least partially defines a series resonant path across the BAW resonator filter; a first shunt SMR BAW resonator, coupled to an output of the first series SMR BAW resonator, that at least partially defines a first shunt resonant path in the BAW resonator filter; a first helper inductor, coupled between the first shunt SMR BAW resonator and ground, that defines a first additional resonant frequency that improves rejection of out-of-band frequencies in the BAW resonator filter and insertion loss; a second series SMR BAW resonator, coupled between the first series SMR BAW resonator and an output of the BAW resonator filter, that further at least partially defines the series resonant path across the BAW resonator filter; a second shunt SMR BAW resonator, coupled to an output of the second series SMR BAW resonator, that at least partially defines a second shunt resonant path in the BAW resonator filter; a second helper inductor, coupled between the second shunt SMR BAW resonator and ground, that defines a second additional resonant frequency that further improves rejection of out-of-band frequencies in the BAW resonator filter; and a third series SMR BAW resonator, coupled between the second series SMR BAW resonator and the output of the BAW resonator filter, that further yet at least partially defines the series resonant path across the BAW resonator filter.