US 12,489,423 B2
Ladder filter including additional resonator for higher attenuation
Koichi Hatano, Yokohama (JP)
Assigned to SKYWORKS SOLUTIONS, INC., Irvine, CA (US)
Filed by SKYWORKS SOLUTIONS, INC., Irvine, CA (US)
Filed on Mar. 16, 2023, as Appl. No. 18/184,779.
Claims priority of provisional application 63/269,796, filed on Mar. 23, 2022.
Prior Publication US 2023/0308080 A1, Sep. 28, 2023
Int. Cl. H03H 9/60 (2006.01)
CPC H03H 9/605 (2013.01) 17 Claims
OG exemplary drawing
 
1. A radio frequency ladder filter comprising:
a plurality of series bulk acoustic wave (BAW) resonators electrically connected in series between an input and an output;
a plurality of shunt BAW resonators electrically connected between nodes between adjacent ones of the plurality of series BAW resonators and ground; and
at least one parallel BAW resonator electrically connected in parallel with one of the plurality of series BAW resonators to increase attenuation in a lower side of a stop band of the radio frequency ladder filter, the at least one parallel BAW resonator having an anti-resonance frequency lower than a lower end frequency of a stop band on a lower side of a passband of the radio frequency ladder filter and a lower capacitance than a capacitance of the one of the plurality of series BAW resonators.