Low pass filter using bulk acoustic wave resonator (BAWR)

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;
• a first BAWR configured to be connected to the input terminal;
• a first ladder being connected to the input terminal and the first BAWR, and comprising a second BAWR, a first inductor, and a third BAWR;
• a second ladder being connected in series with the first ladder, and comprising a fourth BAWR, a second inductor, and a fifth BAWR;
• and
• an output terminal being connected to the second ladder, and configured to be connected with a second RF device,
• wherein the second BAWR and the fourth BAWR are connected in series with each other, the third BAWR and the fifth BAWR are connected in parallel with each other, the second BAWR and the first inductor are connected in parallel with each other, and the fourth BAWR and the second inductor are connected in parallel with each other, and
• 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.

A low pass filter using a bulk acoustic wave resonator (BAWR), the filter comprising:

• an input terminal;
• an output terminal;
• a first series segment having a first bulk acoustic wave resonator (BAWR) and a first inductor connected in parallel;
• a second series segment having a second BAWR and a second inductor connected in parallel;
• a third BAWR connected between a reference potential and the input terminal;
• a fourth BAWR connected between the reference potential and a point between the first and second series segments;
• and
• a fifth BAWR connected between the reference potential and the output terminal;
• wherein the first and second series segments are connected in series between the input and output terminals,
• wherein the third, fourth, and fifth BAWR are connected in parallel, and
• wherein:
• the first BAWR has a same resonance frequency as one of the third, fourth, and fifth BAWRs;
• the second BAWR has a same resonance frequency as one of the third, fourth, and fifth BAWRs;
• or
• the first BAWR has a same resonance frequency as one of the third, fourth, and fifth BAWRs, and the second BAWR has a same resonance frequency as another one of the third, fourth, and fifth BAWRs.