Bulk acoustic wave filters

摘要

In a filter having a half-ladder structure comprising an alternating series of series branches and shunt branches, including a signal input and a signal output related to a common ground, at least one series branch or one parallel branch of the filter is configured as a BAW device comprising a first BAW resonator and a second BAW resonator connected either antiparallel or antiseries. The second harmonic emission generated by the first BAW resonator substantially cancels the second harmonic emission of the second BAW resonator and the second harmonic emission of at least one other series branch or one other parallel branch of the filter. By this method, the filter's second harmonic emissions are reduced.