Resonator, band-pass filter, and duplexer

A band-pass filter comprising at least two resonators,

• wherein the at least two resonators comprise at least one serial resonator and at least one parallel resonator, and
• wherein each of the at least two resonators comprising:
• a first electrode comprising a nonmagnetic conductive material;
• a ferromagnetic fixed layer disposed on the first electrode, the ferromagnetic fixed layer having a fixed magnetization direction;
• a nonmagnetic conductive layer disposed on the ferromagnetic fixed layer;
• a ferromagnetic free layer disposed on the nonmagnetic conductive layer, the ferromagnetic free layer having a magnetization direction which varies with an external magnetic field;
• and
• a second electrode disposed on the ferromagnetic free layer, the second electrode comprising a nonmagnetic conductive material.

A duplexer comprising:

• first and second band-pass filters, each band-pass filter comprising at least two resonators;
• and
• a phase shifter,
• wherein the at least two resonators comprise at least one serial resonator and at least one parallel resonator, and
• wherein each of the at least two resonators comprising:
• a first electrode comprising a nonmagnetic conductive material;
• a ferromagnetic fixed layer disposed on the first electrode, the ferromagnetic fixed layer having a fixed magnetization direction;
• a nonmagnetic conductive layer disposed on the ferromagnetic fixed layer;
• a ferromagnetic free layer disposed on the nonmagnetic conductive layer, the ferromagnetic free layer having a magnetization direction which varies with an external magnetic field;
• and
• a second electrode disposed on the ferromagnetic free layer, the second electrode comprising a nonmagnetic conductive material.