Patent ID: 9035722
Filing Date: 2015-05-19
Classification: H03H

Abstract:
1. A ladder filter comprising: at least one series resonator connected in series between an input terminal and an output terminal; at least one parallel resonator connected in parallel with the at least one series resonator; an additional resonator connected in series between the at least one series resonator and one of the input terminal and the output terminal; and an inductor connected in series to the additional resonator, the additional resonator having a resonance frequency higher than an anti-resonance frequency of the at least one series resonator, wherein a resonance frequency of a resonance circuit formed by the additional resonator and the inductor is located within a pass band of the ladder filter, and wherein the pass band ranges from a resonance frequency of the at least one parallel resonator to the anti-resonance frequency of the at least one series resonator.