Patent ID: 8896396

Claim:
A low pass filter using a bulk acoustic wave resonator (BAWR), the filter comprising: an input terminal configured to be connected with a first radio frequency (RF) device; an output terminal configured to be connected with a second RF device; a parallel segment comprising a first BAWR, a third BAWR, and a fifth BAWR that are connected in parallel with one another to a reference potential; a first series segment having a second BAWR and a first inductor; and a second series segment having a fourth BAWR and a second inductor, and connected in series with the first series segment, wherein a resonance frequency of the second BAWR and a resonance frequency of the fourth BAWR have different values, wherein: the second BAWR has a same resonance frequency as one of the first, third, and fifth BAWRs; the fourth BAWR has a same resonance frequency as one of the first, third, and fifth BAWRs; or the second BAWR has a same resonance frequency as one of the first, third, and fifth BAWRs, and the fourth BAWR has a same resonance frequency as another one of the first, third, and fifth BAWRs; and wherein the output terminal is configured to output to the second RF device one or more signals having a frequency lower than a predetermined frequency among signals input from the first RF device.