Coupled resonator bulk acoustic wave filter

A microwave filter comprising:

• a first piezoelectric acoustic, bulk wave, resonator;
• a second piezoelectric acoustic, bulk wave, resonator acoustically coupled to the first acoustic resonator and disposed above or below the first acoustic resonator;
• a third piezoelectric acoustic, bulk wave, resonator electrically connected to the second acoustic resonator;
• a fourth piezoelectric acoustic, bulk wave, resonator acoustically coupled to the third acoustic resonator and disposed above or below the third acoustic resonator;
• a first plurality of contiguous intervening layers of differing materials located between the first acoustic resonator and the second acoustic resonator and affecting the amount of the acoustic coupling between the first and second acoustic resonators;
• and
• a second plurality of intervening layers of material located between the third acoustic resonator and the fourth acoustic resonator and affecting the amount of the acoustic coupling between the third and fourth acoustic resonators.

A microwave filter having a signal input port and a signal output port and comprising:

• a first acoustic, bulk wave, resonator that includes a piezoelectric layer of insulating material, the first acoustic resonator being electrically connected to the signal input port;
• a second acoustic, bulk wave, resonator acoustically coupled to the first resonator and disposed above or below the first acoustic resonator;
• a third acoustic, bulk wave, resonator that includes a piezoelectric layer of insulating material and that is acoustically coupled to the second resonator and disposed above or below the second acoustic resonator, the third acoustic resonator being electrically connected to the signal output port and the second acoustic resonator being located between the first and third acoustic resonators;
• a first plurality of contiguous intervening layers of differing materials located between the first acoustic resonator and the second acoustic resonator, the first plurality of contiguous intervening layers acoustically coupling the first acoustic resonator with the second acoustic resonator;
• a second plurality of contiguous intervening layers of differing materials located between the second and third acoustic resonators, the second plurality of contiguous intervening layers acoustically coupling the second acoustic resonator with the third acoustic resonator.

A microwave filter comprising:

• a first piezoelectric acoustic, bulk wave, resonator;
• a second piezoelectric acoustic, bulk wave, resonator, the second acoustic resonator being acoustically coupled to the first acoustic resonator and disposed above or below the first acoustic resonator;
• and
• a plurality of contiguous intervening layers of differing materials located between the first acoustic resonator and the second acoustic resonator, the contiguous intervening layers acoustically coupling the first acoustic resonator with the second acoustic resonator and the first acoustic resonator and the second acoustic resonator being acoustically either approximately critically coupled or over-coupled.

An microwave acoustic device fabricated upon a wafer comprising:

• a first microwave filter fabricated upon the wafer and having a pass-band frequency and the first microwave filter comprising:
• a first piezoelectric acoustic, bulk wave, resonator having a conducting electrode;
• a second piezoelectric acoustic, bulk wave, resonator, the second acoustic resonator being acoustically coupled to the first acoustic resonator and disposed above or below the first acoustic resonator;
• and
• a plurality of contiguous intervening layers of differing materials located between the first acoustic resonator and the second acoustic resonator and affecting the amount of the acoustic coupling between the first and second acoustic resonators;
• and a second microwave filter fabricated upon the wafer and having a pass-band frequency and the second microwave filter comprising:
• a first piezoelectric acoustic, bulk wave, resonator having a conducting electrode;
• a second piezoelectric acoustic, bulk wave, resonator, the second acoustic resonator being acoustically coupled to the first acoustic resonator and disposed above or below the first acoustic resonator;
• and
• a plurality of contiguous intervening layers of differing materials located between the first acoustic resonator and the second acoustic resonator and affecting the amount of the acoustic coupling between the first and second acoustic resonators;
• wherein the thickness of the conducting electrode in the first piezoelectric resonator of the first microwave filter differs from the thickness of the conducting electrode in the first piezoelectric resonator of the second microwave filter, whereby said difference in thicknesses causes the pass-band frequency of the first microwave filter to be shifted relative to the pass-band frequency of the second microwave filter.