Duplexer incorporating thin-film bulk acoustic resonators (FBARs)

A band-pass filter, comprising:

• shunt elements;
• and
• series elements, in which:
• the series elements and the shunt elements are connected to form a ladder circuit,
• each of the elements includes a film bulk acoustic resonator (FBAR), and
• at least one of the elements additionally includes an auxiliary inductor in series with the FBAR included therein.

A band-pass filter, comprising:

• shunt elements;
• and
• series elements, in which:
• the series elements and the shunt elements are connected to form a ladder circuit,
• each of the elements includes a film bulk acoustic resonator (FBAR),
• the FBARs each have a resonant frequency,
• the FBARs included in the series elements all have the same resonant frequency,
• the FBARs included in the shunt elements all have the same resonant frequency, different from the resonant frequency of the FBARs included in the series elements, and
• at least one of the elements additionally comprises an auxiliary inductor in series with the FBAR comprised therein.

A band-pass filter, comprising:

• shunt elements;
• and
• series elements, in which:
• the series elements and the shunt elements are connected to form a ladder circuit,
• each of the elements includes a film bulk acoustic resonator (FBAR), and
• the FBARs collectively have more than two different resonant frequencies.