Single cavity acoustic resonators and electrical filters comprising single cavity acoustic resonators

An electrical filter, comprising:

• a single cavity acoustic resonator, comprising:
• a first electrode;
• a second electrode;
• a third electrode disposed between the first electrode and the second electrode, wherein the first and second electrodes comprise a substantially identical thickness, and the third electrode comprises a thickness that is approximately twice as great as the thickness of the first and second electrodes;
• a first piezoelectric layer disposed between the third electrode and the first electrode, and comprising a first C-axis having an orientation;
• and a second piezoelectric layer disposed between the third electrode and the second electrode, and comprising a second C-axis having an orientation parallel to the first C-axis, wherein application of a time varying electrical signal at a drive frequency to either the third electrode or to the first and second electrodes results in a resonance of the single cavity acoustic resonator at approximately twice a fundamental resonant frequency and a cancellation of substantially all even-order mixing products in the single cavity resonator.

A duplexer, comprising:

• a transmit filter;
• and a receive filter, each comprising:
• a single cavity acoustic resonator, comprising:
• a first electrode;
• a second electrode;
• a third electrode disposed between the first electrode and the second electrode, wherein the first and second electrodes comprise a substantially identical thickness, and the third electrode comprises a thickness that is approximately twice as great as the thickness of the first and second electrodes;
• a first piezoelectric layer disposed between the third electrode and the first electrode, and comprising a first C-axis having an orientation;
• and a second piezoelectric layer disposed between the third electrode and the second electrode, and comprising a second C-axis having an orientation parallel to the first C-axis, wherein application of a time varying electrical signal at a drive frequency to either the third electrode or to the first and second electrodes results in a resonance of the single cavity acoustic resonator at approximately twice a fundamental resonant frequency and a cancellation of substantially all even-order mixing products in the single cavity resonator.